Dialysis system having disposable cassette and interface therefore

BACKGROUND

0001The examples discussed below relate generally to medical fluid delivery. More particularly, the examples disclose systems, methods and apparatuses for automated peritoneal dialysis (“APD”).

0002Due to various causes, a person's renal system can fail. Renal failure produces several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible and toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others) can accumulate in blood and tissue.

0003Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that normal functioning kidneys would otherwise remove. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life saving.

0004One type of kidney failure therapy is peritoneal dialysis, which infuses a dialysis solution, also called dialysate, into a patient's peritoneal cavity via a catheter. The dialysate contacts the peritoneal membrane of the peritoneal cavity. Waste, toxins and excess water pass from the patient's bloodstream, through the peritoneal membrane and into the dialysate due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate is drained from the patient, removing waste, toxins and excess water from the patient. This cycle is repeated.

0005There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”), automated peritoneal dialysis (“APD”), tidal flow dialysate and continuous flow peritoneal dialysis (“CFPD”). CAPD is a manual dialysis treatment. Here, the patient manually connects an implanted catheter to a drain, allowing spent dialysate fluid to drain from the peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate, infusing fresh dialysate through the catheter and into the patient. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the peritoneal cavity, wherein the transfer of waste, toxins and excess water takes place. After a dwell period, the patient repeats the manual dialysis procedure, for example, four times per day, each treatment lasting about an hour. Manual peritoneal dialysis requires a significant amount of time and effort from the patient, leaving ample room for improvement.

0006Automated peritoneal dialysis (“APD”) is similar to CAPD in that the dialysis treatment includes drain, fill, and dwell cycles. APD machines, however, perform the cycles automatically, typically while the patient sleeps. APD machines free patients from having to manually perform the treatment cycles and from having to transport supplies during the day. APD machines connect fluidly to an implanted catheter, to a source or bag of fresh dialysate and to a fluid drain. APD machines pump fresh dialysate from a dialysate source, through the catheter, into the patient's peritoneal cavity, and allow for the dialysate to dwell within the cavity and for the transfer of waste, toxins and excess water to take place. The source can be multiple sterile dialysate solution bags.

0007APD machines pump spent dialysate from the peritoneal cavity, though the catheter, to the drain. As with the manual process, several drain, fill and dwell cycles occur during dialysis. A “last fill” occurs at the end of APD, which remains in the peritoneal cavity of the patient until the next treatment.

0008Both CAPD and APD are batch type systems that send spent dialysis fluid to a drain. Tidal flow systems are modified batch systems. With tidal flow, instead of removing all of the fluid from the patient over a longer period of time, a portion of the fluid is removed and replaced after smaller increments of time.

0009Some continuous flow, or CFPD, systems clean or regenerate spent dialysate instead of discarding it. Others use a large volume of fresh dialysate. The systems pump fluid into and out of the patient, through a loop. In a regenerating system, dialysate flows into the peritoneal cavity through one catheter lumen and out another catheter lumen. The fluid exiting the patient passes through a reconstitution device that removes waste from the dialysate, e.g., via a urea removal column that employs urease to enzymatically convert urea into ammonia. The ammonia is then removed from the dialysate by adsorption prior to reintroducing the dialysate into the peritoneal cavity. Additional sensors are employed to monitor the removal of ammonia. Regenerating CFPD systems are typically more complicated than batch systems.

0010Peritoneal dialysis (“PD”) systems, home hemodialysis/hemofiltration, and intensive care unit procedures that use bagged peritoneal dialysate, hemodialysis dialysate, or hemofiltration substitution solution can use a dual chamber bag. For example, bicarbonate based solutions have been developed for certain ones of the above applications. Bicarbonate is unstable in the presence of magnesium and calcium and forms a precipitate after a period of time. The bicarbonate based solutions are accordingly provided in a dual chamber bag. Prior to use, a seal between the two chambers is broken and the two concentrate solutions are mixed and used before calcium or magnesium precipitate can form. Unfortunately, a single concentrate solution delivered to a patient due to the two concentrate solutions not mixing can create a physiologically unsafe condition for the patient.

0011The system below addresses various drawbacks with the above-mentioned medical fluid treatments.

SUMMARY

0012The present disclosure describes an improved automated peritoneal dialysis (“APD”) system, however, many of the teachings herein are applicable to other medical fluid treatments, especially other renal failure therapy treatments, such as hemodialysis (“HD”), hemofiltration (“HF”), hemodiafiltration (“HDF”) and continuous renal replacement therapy (“CRRT”).

0013The system offers improved treatment and ease of use features. The system is mobile in one embodiment so that the patient can, for example, start a therapy in the family room and move the system to a bedroom on the same floor. The system manages supply bags, which are carried with the device or instrument when the patient moves the instrument. The system also employs a bag management system, which tilts the supply bags so that gravity will cause fluid to flow from them, leaving air behind during the priming sequence and normal operation. The gravity induced air separation at the supply bags allows the system to pump at high flowrates because there is little concern that the air has not been removed properly while pumping the fluid.

0014The system provides a cart having a rotating bearing plate or “lazy Susan” that supports the instrument and allows it to be rotated for convenient operation, making at least the vast majority of system features readily accessible. This may allow the patient to correct most alarms without getting out of bed. The “lazy Susan” plate can optionally have detent positions every ninety degrees or so.

0015The system includes an improved priming procedure using a patient line having dual lumens. During the patient line prime, fluid flows down one lumen away from a disposable cassette and back up the other lumen towards the cassette forming a closed loop feedback that indicates when priming is complete. This feedback is operable even with patient line extensions. U.S. Patent Application No. 2004/0019312 A1, FIG. 2, owned by the eventual assignee of the present disclosure, shows a tip protector for a dual lumen patient line that is compatible with this priming technique. The dual lumen line also eliminates the volume of spent effluent fluid that is pushed back (recirculated) when the instrument cycles from drain to fill. Additionally, the dual lumen line accommodates the sensing of intraperitoneal pressure (“IPP”) to optimize patient fill and drain volumes as described in U.S. Pat. No. 6,497,676, owned by the eventual assignee of the present disclosure, the entire contents of which are incorporated expressly herein by reference. Further still, the dual lumen patient line allows the same disposable set to be used for large and small patients because the recirculation volume is near zero.

0016The system also provides an auto-connection mechanism that connects connectors from the supply bags to connectors of the cassette supply lines. In one embodiment, the system provides for up to four supply bags, which can be connected to a manifold of the auto-connection mechanism. Each solution bag can be the same or different. The auto-connection mechanism is advantageously able to use the same solution bag (e.g., made having existing spikes and spike septums with existing equipment and processes). Tip protectors which protect the supply and bag pigtail connectors are modified to be compatible with the auto-connection mechanism.

0017As discussed in detail below, the system of the present disclosure is readily adapted for a high-volume therapy. In one implementation, the system uses four-to-one manifolds, which allow any one or more of four supply bag inlets to the disposable cassette to be increased to up to four bags for treatment. The four-to-one manifolds work in conjunction with the auto-connection and auto-identification systems described herein. Up to four, four-to-one manifolds, each manifold being able to connect to up to four (e.g., same solution) supply bags, can accommodate a therapy volume of, for example, up to ninety-six liters.

0018Each of the manifold lines in the four-to-one manifold is placed in the auto-connection mechanism for connection to the supply lines connected to the disposable cassette. The single supply line of the disposable cassette can now connect to up to four solution bags. An imaging system recognizes the four to one connector and the type of attachment made to the manifold (the one line) end of the four to one manifold.

0019The auto-connection system also includes an automatic clamping system, which allows the user to not have to clamp and unclamp solution lines during the connection process or when an alarm condition occurs.

0020An imaging system or solution identification system verifies the volume, expiration date, composition, and configuration (e.g., single bag solution, multiple chamber bag solution, or multiple bag solution that requires mixing) before the bags are connected. The solution identification system verifies that the composition and volume of the solutions are consistent with the therapy prescription before connection. The solution identification system also: (i) automatically draws solution in the correct sequence when the correct solution bags are loaded; (ii) informs the user if the incorrect solution bags are loaded; and (iii) alerts the user if a solution bag connector is deformed, potentially causing an improper connection.

0021The disposable set (cassette, bags and lines) of the system is relatively simple and easy to use and requires fewer product codes because all geographic regions can use the same disposable set for both pediatric patients and adult patients, and with therapy volumes up to ninety-six liters. The lines of the disposable set are connected to organizers (e.g., cassette supply lines connected to a first organizer and patient and drain lines connected to a second organizer), which prevent the lines from becoming tangled and facilitate loading the lines into the auto-connection system.

0022The disposable set allows for admixing as described in U.S. Pat. No. 5,925,011, owned by the eventual assignee of the present disclosure, the entire contents of which are incorporated expressly herein by reference, or for the delivery of single part solutions, or double part solutions contained in a single bag. If a peel seal or frangible seal needs to be broken before use, the system can verify that it has been broken before the solution is delivered to the patient. Capacitive sensors located on the bag management shelves are used to verify that the seal has been broken and that the same solution is present in both chambers (ends) of the solution bag.

0023In an alternative embodiment, the sensor is an inductive sensor, which can (i) detect whether a emitter chamber bag has been loaded properly onto one of the bag management shelves and (ii) detect whether a frangible seal between two chambers bags has been broken such that the concentrate solutions can mixed properly for delivery to the patient. The inductive sensing apparatus and method are not limited to renal applications and can be used to confirm placement, mixing, etc., for any medical fluid system using dual or multi-chamber bagged solutions.

0024The system further provides a non-invasive temperature measuring feature or technique. The heat sensing technique uses a non-invasive infrared temperature sensor and electromagnet. The electromagnet controls the orientation of the temperature sensor. The disposable cassette has sheeting with a black or opaque area. A first orientation of the infrared sensor is trained on the black or opaque area and consequently measures the temperature of the sheeting. The second orientation of the infrared sensor is trained on an area of the sheeting which is not black or opaque and can thus see through the sheeting into the fluid behind the sheeting. This second infrared sensor reading measures a combination of the temperature of the film and the fluid. Discussed herein are algorithms for calculating the temperature of the fluid from the two infrared temperature readings.

0025The HomeChoice® APD System marketed by the eventual assignee of the present disclosure, uses a method described in U.S. Pat. No. 4,826,482 (“The '482 Patent”), to determine the volume of fluid pumped to the patient or to the drain. That method in essence looks backwards after a pump stroke to see how much fluid has been pumped to the patient. While this system has been highly successful, there are various reasons to know the volume of fluid pumped during the pump stroke or in real time. The reasons are discussed in detail below but in general include: (i) being able to fill/drain a patient to a volume that is not equal to a whole number of pump strokes; (ii) being able to immediately know when a patient is drained to empty or virtually empty to reduce pain at the end of drain; (iv) providing accuracy needed for mixing solutions; and (v) helping to eliminate the need to have to provide an alternate source of fluid, so that a partially full pump chamber can be differentiated from a pump chamber containing air and fluid.

0026The real time system and method in one embodiment monitors the pressure decay in a pressurized tank in fluid communication with the pump chamber of the disposable cassette. The system knows the volume of air or gas (V_gas) in the pump chamber prior to opening the valve to the tank. Then, after the valve to the tank is opened the system takes pressure readings at desired intervals and performs a calculation after each reading. The initial pressure (P<b>1</b>) in the tank is known. If the pressure at any given point in time is taken as P<b>1</b>′ then a ratio can be expressed in an equation form as follows: <br />((P1/P1′)−1),<br /> this ratio is multiplied by an addition of the gas volume V_gasto a known volume of the tank V_tankto form a real time volume of fluid pumped V_fluid=((P<b>1</b>/P<b>1</b>′)−1)(V_tank+V_gas). P<b>1</b> is initially equal to P<b>1</b>′, thus making the initial real time volume of fluid pumped equal to zero. As P<b>1</b>′ becomes increasingly less than P<b>1</b> over time, ((P<b>1</b>/P<b>1</b>′)−1) becomes increasingly larger over time as does V_fluid.

0027The real time volumes are useful for many purposes as described above. Described below is an algorithm for using the real time volumes to determine features such as: (i) if a full pump stroke has occurred; (ii) if a line occlusion has occurred; (iii) if a leak has occurred; and (iv) if multiple concentrates have been mixed properly, for example.

0028The cassette in one embodiment has sheeting welded to the molded plastic piece as described in U.S. Pat. Nos. 5,401,342, 5,540,808, 5,782,575 and 6001201. In an alternative embodiment, the molded plastic piece is enclosed within welded sheeting but not welded to the sheeting. The sheeting in one embodiment is welded to itself and to the tubing attached to the cassette, allowing the inside of the sheeting, including the molded plastic piece, to be isolated from the environment. This cassette assembly provides flexibility in material selection for the molded plastic, sheeting and tubing because the sheeting to molded plastic seal has been eliminated. The sheeting material therefore does not need to be compatible with the rigid cassette material from a welding or bonding standpoint.

0029A disposable cassette having three pumping chambers is also shown and described below. The three chamber cassette provides a number of advantages, such as allowing for continuous flow at both the inlet and outlet of the pump even when running a standard, e.g., batch, therapy. With two pump chambers, fluid measurement is performed in an attempt to make patient flow essentially continuous. For example, the fluid measurements can be made in one pump chamber, while the other pump chamber is halfway through its pump stroke and vice versa. Nevertheless, the fresh supply and drain flowrates are pulsatile because more fluid will be flowing at certain times than at others. The three pump cassette therefore allows for continuous flow to a patient even when two solutions are being mixed online.

0030The system also includes an improved cassette/manifold membrane assembly or system. The assembly or system includes an interface plate having pump actuation areas with actuation ports for allowing a positive or negative pressure to be applied within the pump actuation areas to the membrane gasket to correspondingly place a positive or negative pressure on a juxtaposed flexible sheeting of the disposable cassette. Likewise, the interface plate includes valve actuation areas with actuation ports for allowing a positive or negative pressure to be applied within the valve actuation areas to the membrane gasket to correspondingly place a positive or negative pressure on the juxtaposed flexible sheeting of the disposable cassette. In addition to the actuation ports, the cassette interface includes an evacuation port to evacuate air between the membrane gasket and cassette sheeting adjacent to each pump and each valve.

0031The gasket includes blind holes that seal around the sidewalls of the actuation ports of the valves or pump chambers. The blind holes include a sheath or thin portion that extends over the valve or pump actuation ports. Positive or negative pressure applied through actuation ports is therefore likewise applied to the sheath portion of the blind hole of the members. Positive or negative pressure applied to the sheath portion accordingly causes a flexing of the sheath portion and corresponding flexing of the cassette sheeting.

0032The membrane also provides a through-hole for each evacuation port of the interface plate. The through-holes seal around the sidewalls of the protruding evacuation ports and allow a negative pressure applied through the evacuation ports to suck the cassette sheeting against the sheath portions of the membrane gasket forming pump or valve areas. In this manner, for a given pump or valve area, the membrane gasket and cassette sheeting flex back and forth together.

0033If a hole develops in either the membrane gasket or the cassette sheeting, the vacuum level through the evacuation port at the leak decreases, indicating the leak. Thus the evacuation ports also serve as leak detectors that are placed in multiple places over the cassette, providing superior leak detection with the capability of indicating where on the cassette sheeting or membrane gasket the leak has occurred. This leak detection capability is present prior to the beginning of therapy as well as during therapy.

0034The system can also tell which of the membrane gasket and the cassette sheeting has incurred a leak. If fluid is not drawn between the membrane gasket and the sheeting, the leak is in the membrane gasket. If fluid is drawn in between the membrane gasket and the sheeting, the leak is in the cassette sheeting. This can be a valuable tool, for example, in diagnosing a machine that appears to be malfunctioning.

0035The cassette interface, in an embodiment, also integrates the pneumatic manifold with the cassette interface so that air that travels from the back side of the pumping chambers of the disposable cassette to the volumetric reference chambers (one for each pump chamber, used for volumetric accuracy calculation and air) of the pneumatic manifold does not have to travel far. The close spacing also tends to make the temperature of air in the passageways, the reference chambers and the pump chambers equal. This is useful for a pneumatic pumping technique that assumes a constant temperature between air in the volumetric reference chambers and the medical fluid or dialysate pumped though the disposable cassette. The dialysate is located on the other side of the cassette sheeting from air in communication with the pneumatic source and the volumetric reference chamber. The fluid temperature needs to be about that of the human body, e.g., about 37° C. The air in the reference chamber therefore should be about 37° C.

0036The system in one embodiment provides a heater at the cassette interface, which heats the interface plate, the volumetric reference chambers and the pneumatic passageways to a single temperature to stabilize the entire pneumatic circuit at a desired temperature. The heated interface plate also enables the reference chambers to be brought to temperature more quickly, especially on cold days. A quick warm-up also saves a substantial amount of time during the calibration of the system. The interface plate in one embodiment is made entirely of metal, which can be heated. Alternatively, a cassette interface portion of the manifold, to which pneumatic control valves controlling pressure to the fluid valves are attached, is plastic. The reference chambers are metal and are provided in a module with a heating element, such as a resistive heating element. The module is affixed to the plastic interface. The interface includes pump chamber walls having a metal or thermally conductive section. Heat is thereby transferred to the pump chamber interface wall, which heats air therein.

0037It is therefore an advantage of the present disclosure to provide an improved medical fluid system, such as for APD, HD, HF, HDF and CRRT.

0038It is another advantage of the present disclosure to provide a medical fluid system having a rotatable base, making device features readily accessible.

0039Moreover, it is an advantage of the present disclosure to provide a medical fluid system that is relatively mobile and that carries the supply bags as the system is moved.

0040It is a further advantage of the present disclosure to provide a medical fluid system that positions fluid supply bags so as to tend to trap air in the bags.

0041Another advantage of the present disclosure is to provide a non-invasive temperature sensing apparatus and method.

0042It is yet a further advantage of the present disclosure to provide a disposable cassette wherein at least one of: (i) the cassette includes three pumping chambers; and (ii) the molded plastic part of the cassette is provided inside a pouch made of flexible sheeting sealed together and to tubing attached to the molded plastic part.

0043It is still another advantage of the present disclosure to provide a method and apparatus for real time measurement of fluid volume pumped.

0044Further still, it is an advantage of the present disclosure to provide a fluid management system (“FMS”), which has improved temperature control for a fluid volume measuring system using the ideal gas law.

0045Yet another advantage of the present disclosure is to provide for improved leak detection in a pneumatically actuated pumping system.

0046Still further, it is an advantage of the present disclosure to provide an improved cassette/manifold membrane gasket.

0047Yet a further advantage of the present disclosure is to provide an auto-connection mechanism for solution lines and an auto-identification mechanism to ensure that a proper solution at a proper volume for a particular supply bag will be delivered to a patient.

0048Still a further advantage of the present disclosure is to provide an improved priming technique using a dual lumen patient line and an apparatus and method for automatically connecting the dual lumen patient line to a dual port transfer set.

0049Further still, an advantage of the present disclosure is to provide an apparatus and method for automatically detecting whether a solution bag has been loaded for therapy.

0050A related advantage is to use the above bag detection apparatus and method for automatically detecting whether a multi-chamber solution bag has been opened properly so that the solution inside is mixed properly for delivery to the patient.

0051A further related advantage is that the above bag detection apparatus and method is non-invasive, maintaining the sterility of the concentrates and preserving the bag and other solution disposables.

0052Additional features and advantages are described herein, and will be apparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

0053<figref idref="DRAWINGS">FIG. 1</figref> illustrates one embodiment of a dialysis system cart with a machine holding, rotatable bearing.

0054<figref idref="DRAWINGS">FIG. 2</figref> illustrates the cart of <figref idref="DRAWINGS">FIG. 1</figref>, in which the dialysis machine has been rotated to have the solution bags facing a front of the cart.

0055<figref idref="DRAWINGS">FIG. 3</figref> illustrates a system using the cart of <figref idref="DRAWINGS">FIG. 1</figref>, in which the dialysis machine has been rotated to have machine controls facing a front of the cart.

0056<figref idref="DRAWINGS">FIGS. 4 to 9</figref> illustrate one embodiment for a supply bag loading procedure for a bag management system of a dialysis system of the present disclosure.

0057<figref idref="DRAWINGS">FIG. 10</figref> is a perspective view of one embodiment of a disposable set of the system of the present disclosure.

0058<figref idref="DRAWINGS">FIG. 11</figref> is a perspective view of one embodiment of a four-to one manifold useable with the disposable set of <figref idref="DRAWINGS">FIG. 10</figref>.

0059<figref idref="DRAWINGS">FIG. 12</figref> is a perspective view of one embodiment of an instrument of the system of the present disclosure, which includes an auto-connection mechanism operable with the disposable set of <figref idref="DRAWINGS">FIG. 10</figref>.

0060<figref idref="DRAWINGS">FIGS. 13A to 13I</figref> are perspective views illustrating one embodiment of a supply line auto-connection sequence using the auto-connection mechanism of <figref idref="DRAWINGS">FIG. 12</figref>.

0061<figref idref="DRAWINGS">FIG. 14</figref> is a perspective view of one embodiment of an auto-identification mechanism operable with the auto-connection mechanism of <figref idref="DRAWINGS">FIG. 12</figref>.

0062<figref idref="DRAWINGS">FIGS. 15A to 15E</figref> illustrate one embodiment of a patient line auto-connection sequence using the auto-connection mechanism of <figref idref="DRAWINGS">FIG. 12</figref>.

0063<figref idref="DRAWINGS">FIG. 16</figref> is a perspective view of one embodiment for a disposable pumping cassette having a rigid portion held in a sealed pump sheeting pouch.

0064<figref idref="DRAWINGS">FIGS. 17A and 17B</figref> are front and rear views, respectively, of one embodiment of a disposable pumping cassette having three pump chambers.

0065<figref idref="DRAWINGS">FIG. 17C</figref> shows one possible valve arrangement for the three pump chamber cassette of <figref idref="DRAWINGS">FIGS. 17A and 17B</figref> for achieving the pumping regimes shown in connection with <figref idref="DRAWINGS">FIGS. 18A to 18C</figref>.

0066<figref idref="DRAWINGS">FIGS. 18A to 18C</figref> are schematic views showing pumping sequences using the three pump chamber cassette of <figref idref="DRAWINGS">FIGS. 17A and 17B</figref>.

0067<figref idref="DRAWINGS">FIG. 19</figref> is a perspective view of one embodiment of a pneumatic pumping system of the present disclosure, which includes a manifold cassette interface, a membrane gasket and a disposable cassette.

0068<figref idref="DRAWINGS">FIG. 20</figref> is a perspective view of a manifold cassette interface and membrane gasket of the pneumatic pumping system of <figref idref="DRAWINGS">FIG. 19</figref>.

0069<figref idref="DRAWINGS">FIG. 21</figref> is a perspective view of an interface plate of the cassette interface of the pneumatic pumping system of <figref idref="DRAWINGS">FIG. 19</figref>.

0070<figref idref="DRAWINGS">FIG. 22</figref> is a perspective view of a membrane gasket of the pneumatic pumping system of <figref idref="DRAWINGS">FIG. 19</figref>.

0071<figref idref="DRAWINGS">FIG. 23</figref> is a perspective view of the reverse side of the interface plate of <figref idref="DRAWINGS">FIG. 21</figref>, which is metallic and can include a heating strip for heating the reference chambers formed in the interface plate.

0072<figref idref="DRAWINGS">FIG. 24</figref> is a perspective view of a reverse side of an alternative manifold, which includes a plastic interface and control valve connection portion and a heated reference chamber module connected to the plastic portion.

0073<figref idref="DRAWINGS">FIGS. 25A and 25B</figref> are front and rear perspective views of the plastic interface and control valve connection portion of the assembly of <figref idref="DRAWINGS">FIG. 24</figref>.

0074<figref idref="DRAWINGS">FIGS. 26A and 26B</figref> are front and rear perspective views of the heated reference chamber module of the assembly of <figref idref="DRAWINGS">FIG. 24</figref>.

0075<figref idref="DRAWINGS">FIG. 27</figref> is a schematic view of an embodiment of a pneumatic system for operating a real time method for determining volume of fluid moved.

0076<figref idref="DRAWINGS">FIGS. 28A to 28F</figref> illustrate one embodiment of a real time method for determining volume of fluid moved.

0077<figref idref="DRAWINGS">FIG. 29</figref> is a chart of real time fluid volumes calculated via the method of <figref idref="DRAWINGS">FIGS. 28A to 28F</figref>.

0078<figref idref="DRAWINGS">FIG. 30</figref> is a schematic flow chart illustrating an example of pneumatically actuated pumps undergoing a fill with fresh fluid phase, using the real time method discussed in connection with <figref idref="DRAWINGS">FIGS. 28A to 28F</figref>, and wherein the dialysis system employs inline mixing of dextrose and bicarbonate concentrates.

0079<figref idref="DRAWINGS">FIG. 31</figref> is a schematic flow chart illustrating an example of the pneumatically actuated pumps undergoing a fill with effluent (draining fluid from the patient) phase, using the real time method discussed in connection with <figref idref="DRAWINGS">FIGS. 28A to 28F</figref>.

0080<figref idref="DRAWINGS">FIG. 32</figref> is a schematic view of one embodiment for a non-invasive temperature sensing system and method having a temperature sensor in a first position.

0081<figref idref="DRAWINGS">FIG. 33</figref> is a schematic view of one embodiment for a non-invasive temperature sensing system and method having a temperature sensor in a second position.

0082<figref idref="DRAWINGS">FIG. 34</figref> is a graph comparing the results of the temperature sensing system of <figref idref="DRAWINGS">FIGS. 32 and 33</figref> versus those of an invasive temperature sensor.

0083<figref idref="DRAWINGS">FIG. 35</figref> is a schematic illustration of one embodiment of an inductive solution container loading system in a “not mixed” sensing state.

0084<figref idref="DRAWINGS">FIG. 36</figref> is a schematic illustration of the system embodiment of <figref idref="DRAWINGS">FIG. 35</figref> in a “mixed” sensing state.

0085<figref idref="DRAWINGS">FIGS. 37A to 37D</figref> are schematic views of one embodiment of an inductive sensing system employing multiple emitters and receiving the system capable of orientation detector supply container loading.

DETAILED DESCRIPTION

Mobile Cart System

0086Referring now to the drawings and in particular to <figref idref="DRAWINGS">FIGS. 1 to 3</figref>, a dialysis system, such as an automated peritoneal dialysis (“APD”) system <b>10</b> is illustrated. It should be appreciated that system <b>10</b> can be used with other types of renal failure therapy systems, such as any of those maintained above.

0087<figref idref="DRAWINGS">FIGS. 1 to 3</figref> illustrate that system <b>10</b> includes a mobile cart <b>12</b>, which allows the system to be moved readily, e.g., from a family room to a bedroom and vice versa. Cart <b>12</b> includes a lazy Susan-type bearing <b>14</b>, which provides ample access to the controls <b>22</b> and bag management system <b>30</b> of an instrument <b>20</b> at all times. Bag management system <b>30</b> organizes the loading of supply bags at the beginning of therapy as shown in detail herein. Lazy Susan bearing <b>14</b> in one embodiment is equipped with detents that prevent the system from rotating during operation. A cut-out or hole in the center of lazy Susan bearing <b>14</b> allows a power cord to pass through to shelves <b>16</b> of cart <b>12</b>. Lazy Susan bearing <b>14</b> can also have a total rotation limit, e.g., 360 degrees or so, to prevent damage to the power cord due to over-rotation.

0088As shown specifically in <figref idref="DRAWINGS">FIG. 2</figref>, instrument <b>20</b> can, for example, be rotated to face the patient to provide ready access to the bag management shelves of bag management system <b>30</b>. As shown specifically in <figref idref="DRAWINGS">FIG. 3</figref>, instrument <b>20</b> can then be rotated to provide optimum access to the controls <b>22</b>, display <b>24</b>, auto-connection mechanism <b>26</b> and cassette loading mechanism <b>28</b> during the set-up procedure. Also, instrument <b>20</b> can be rotated so that the display <b>24</b> and controls <b>22</b> face the patient's bed when the patient is asleep. Here, if an alarm sounds, the patient can potentially access controls <b>22</b>, drain line, supply bags lines, etc., without getting out of bed.

0089Mobile cart <b>12</b> includes shelves or drawers <b>16</b>, which hold the ancillary supplies needed for a dialysis therapy. To move system <b>10</b>, the patient needs to unplug a power cord. Mobile cart <b>12</b> accommodates the drain bag, e.g., on lower shelf <b>16</b>. The self-contained drain cart allows cart <b>12</b> to be moved without having to first load the drain bag. If a drain line is run to a house drain instead of a bag, the drain line likely has to be removed from the drain and placed onto cart <b>12</b> when system <b>10</b> is moved. A handle <b>18</b> facilitates moving system <b>10</b> and in one embodiment can be rotated upwardly for movement of cart <b>12</b> and downwardly and out of the way when not needed.

Bag Management System

0090Referring now to <figref idref="DRAWINGS">FIGS. 4 to 9</figref>, an embodiment for bag management system <b>30</b> of dialysis system <b>10</b> is illustrated. As illustrated, bag management system <b>30</b> is connected to or made integral with instrument or cycler <b>20</b>. Bag management system <b>30</b> as illustrated is configured for four, e.g., six liter supply bags <b>40</b><i>a </i>to <b>40</b><i>d </i>(referred to herein collectively as supply bags <b>40</b> or generally, individually as supply bag <b>40</b>). System <b>30</b> is configured alternatively to hold more or less six liter bags <b>40</b>. <figref idref="DRAWINGS">FIGS. 4 to 9</figref> also show that cycler <b>20</b> includes a hinged display <b>24</b>, which can operate with separate controls <b>22</b> and/or a touch screen overlay.

0091<figref idref="DRAWINGS">FIG. 4</figref> shows bag management system <b>30</b> with each of shelves <b>32</b>, <b>34</b>, <b>36</b> and <b>38</b> rotated down and no supply bags <b>40</b> loaded. <figref idref="DRAWINGS">FIG. 5</figref> shows bag management system <b>30</b> with lower shelf <b>32</b> folded down and shelves <b>34</b>, <b>36</b> and <b>38</b> rotated upwardly and out of the way to provide access to bottom shelf <b>32</b>. In an embodiment, the shelves are configured in a cascading or telescoping manner such that third shelf <b>36</b> can fold or rotate into upper shelf <b>38</b>, second shelf <b>34</b> can fold or rotate into third shelf <b>36</b> and lower shelf <b>32</b> can fold or rotate into second shelf <b>34</b>. The hinges of the shelves can have releasably interlocking apparatuses (e.g., mating tabs and detents) that hold the shelves releasably in place when folded or rotated upwardly. Alternatively or additionally, the shelves can releasably lock one to another, e.g., third shelf <b>36</b> locking to upper shelf <b>38</b>, second shelf <b>34</b> locking to third shelf <b>36</b>, and so on. For example, interlocking tabs and detents <b>42</b> and <b>44</b>, respectively, are provided at the sides or gussets of the shelves so that the locking mechanisms <b>42</b> and <b>44</b> do not interfere with the bags <b>40</b> when loaded.

0092<figref idref="DRAWINGS">FIG. 6</figref> shows bag management system <b>30</b> with lower shelf <b>32</b> folded down, a first supply bag <b>40</b><i>a </i>loaded onto lower shelf <b>32</b>, and shelves <b>34</b>, <b>36</b> and <b>38</b> hinged upwardly and out of the way. <figref idref="DRAWINGS">FIG. 7</figref> shows bag management system <b>30</b> with lower shelf <b>32</b> and second shelf <b>34</b> folded down, first supply bag <b>40</b><i>a </i>loaded onto lower shelf <b>32</b>, a second supply bag <b>40</b><i>b </i>loaded onto second shelf <b>34</b>, and shelves <b>36</b> and <b>38</b> hinged upwardly and out of the way.

0093<figref idref="DRAWINGS">FIG. 8</figref> shows bag management system <b>30</b> with lower shelf <b>32</b>, second shelf <b>34</b> and third shelf <b>36</b> folded down, first supply bag <b>40</b><i>a </i>loaded onto lower shelf <b>32</b>, second supply bag <b>40</b><i>b </i>loaded onto second shelf <b>34</b>, a third supply bag <b>40</b><i>c </i>loaded onto third shelf <b>36</b>, and shelve <b>38</b> hinged upwardly and out of the way. <figref idref="DRAWINGS">FIG. 9</figref> shows bag management system <b>30</b> with lower shelf <b>32</b>, second shelf <b>34</b>, third shelf <b>36</b> and top shelf <b>38</b> all folded down, first supply bag <b>40</b><i>a </i>loaded onto lower shelf <b>32</b>, second supply bag <b>40</b><i>b </i>loaded onto second shelf <b>34</b>, third supply bag <b>40</b><i>c </i>loaded onto third shelf <b>36</b>, and fourth supply bag <b>40</b><i>d </i>loaded onto top shelf <b>38</b>.

0094Each tray in the bag management system <b>30</b> folds up providing easy access to the shelf below. When used with cart <b>12</b> above, system <b>30</b> minimizes the height to which patients have to lift the solution bags. The shelf holds solution bags <b>40</b> elevationally above a heater, which can be located at the bottom of instrument <b>20</b> for example, and orients the bag so that the bag outlet port resides below the rest of the bag. The configuration causes dialysis fluid to flow from the bags until empty, leaving any air trapped in the empty bags. This shelf configuration, bag placement and orientation can enhance the volumetric pumping speed and accuracy of the fluid delivery pumps when fluid is pumped directly from the supply bags, e.g., through an inline heater, and into the patient since air does not flow downhill, e.g., from a bag <b>40</b> into a pumping chamber of cassette <b>28</b>.

0095One or more or all of shelves <b>32</b> to <b>38</b> can employ a sensor operable with a sensing system stored in memory. The sensor and associated system perform multiple functions. One function is to determine if a dual chamber or multiple chamber bag has been opened to allow two or more concentrates to mix to form a dialysis fluid that can be pumped to the patient. Sensing a properly opened bag can be a prerequisite for the pumps and/or valves or occludes to operate. The sensors can also detect which shelves <b>32</b> to <b>38</b> have bags and which do not and thus whether enough fluid has or can be connected. One suitable sensor and associated system is found in copending patent application Ser. No. 11/773,501, filed Jul. 5, 2007, entitled, “Apparatus and Method For Verifying A Seal Between Multiple Chambers”, assigned for the eventual assignee of the present disclosure, the entire contents of which are hereby incorporated by reference and relied upon. An alternative inductive sensing apparatus and method is discussed below beginning at <figref idref="DRAWINGS">FIG. 35</figref>.

Disposable Set

0096Referring now to <figref idref="DRAWINGS">FIGS. 10 and 11</figref>, an embodiment of a disposable set <b>50</b> for system <b>10</b> is illustrated. <figref idref="DRAWINGS">FIG. 10</figref> illustrates that disposable set <b>50</b> includes disposable cassette <b>28</b> and supply bags <b>40</b> as discussed above. Bags <b>40</b> in an embodiment each include a solution line or pigtail <b>46</b><i>a </i>to <b>46</b><i>d </i>(referred to herein collectively as pigtails <b>46</b> or generally, individually as pigtail <b>46</b>), which connect to a first set of supply lines <b>48</b><i>a</i>. Solution lines or pigtails <b>46</b> in one embodiment terminate in female connectors <b>56</b> protected by tip protector <b>66</b><i>a</i>. Connectors <b>56</b> in one embodiment are female connectors protected by a pierceable cover. Disposable set <b>50</b> can include a second set of supply lines <b>48</b><i>b </i>for a high-volume therapy as discussed below. First and second supply line sets, <b>48</b><i>a </i>and <b>48</b><i>b </i>respectively, each include multiple lines ending in a connector <b>58</b> protected by a tip protector <b>66</b><i>b</i>. Connectors <b>58</b> can be male spike connectors that spike through the protective covers of female connectors <b>56</b> of bag lines <b>46</b>.

0097Disposable set <b>50</b> also includes a patient line <b>52</b> and drain line <b>54</b>. Patient line <b>52</b> can be a dual lumen line in which one line terminates in a pierceably sealed female connector <b>56</b> protected by a tip protector <b>66</b><i>a </i>and the other line terminates in a spike connector <b>58</b> protected by a tip protector <b>66</b><i>b </i>(see <figref idref="DRAWINGS">FIGS. 15A to 15D</figref>). Drain line terminates in one embodiment with a spike receptacle less a septum, so that a supply bag cannot be connected to the drain line.

0098Pigtails <b>46</b> in one embodiment terminate in female connectors <b>56</b> protected by tip protector <b>66</b><i>a</i>. Connectors <b>56</b>/tip protectors <b>66</b><i>a </i>are held together in a single organizer in one embodiment. Patient line <b>52</b> can be a single lumen patient line (batch dialysis) or a dual lumen patient line (for batch or continuous dialysis) as desired. The first set of supply lines <b>48</b><i>a</i>, patient line <b>52</b> and drain line <b>54</b> are each connected to cassette <b>28</b>.

0099<figref idref="DRAWINGS">FIG. 10</figref> further illustrates one embodiment for a high volume disposable set (e.g., eight bags), which is provided by teeing a second set of supply lines <b>48</b><i>b </i>off of the first set of supply lines <b>48</b><i>a </i>(connected to cassette <b>28</b>) and providing an organizer for holding four spike connectors <b>58</b> on the end of each supply line <b>48</b><i>a </i>or <b>48</b><i>b</i>. The spikes and organizers can be integrated into a single molded spike bundle that contains the spikes and features for gripping and holding the bundle during set up and operation. Each spike connector <b>58</b> of each supply line can connect fluidly and sealingly with a female connector <b>56</b> at the end of each supply bag pigtail <b>46</b>. As mentioned, each spike connector <b>58</b> is protected by its own tip protector <b>66</b><i>b</i>. Line clamps <b>62</b> are provided on the first set of supply lines <b>48</b><i>a</i>. The clamps can be used to occlude the first set of supply lines <b>48</b><i>a </i>before an auto-connection mechanism (discussed below) disconnects connectors <b>58</b> of the first set of supply lines <b>48</b><i>a </i>from connectors <b>56</b> at the end of pigtails <b>46</b>. The auto-connection mechanism can then connect the second set of supply lines <b>48</b><i>b </i>to a second set of supply bags <b>40</b> (not illustrated).

0100<figref idref="DRAWINGS">FIG. 11</figref> illustrates a second embodiment for producing a high-volume disposable set <b>50</b>. Here, the first set of supply tubes <b>48</b><i>a </i>is converted to a high volume set via four-to-one manifold <b>60</b>. Four-to-one manifold <b>60</b> in one embodiment has at one end the same organizer holding four lines <b>48</b><i>c </i>terminating in spike connectors <b>58</b>/tip protectors <b>66</b><i>b </i>as that described above for the supply lines <b>48</b><i>a </i>and <b>48</b><i>b</i>. Manifold <b>60</b> can therefore itself be connected to up to four supply bags <b>40</b>. A connector <b>56</b>/tip protector <b>66</b><i>a </i>of a single input line <b>64</b> from four-to-one manifold <b>60</b> is then inserted into the auto-connection mechanism (described below) in lieu of the connector <b>56</b>/tip protector <b>66</b><i>a </i>at the end of pigtail <b>46</b> of a single supply bag <b>40</b>. An auto-identification system described below automatically tracks the number of bags connected to each four-to-one manifold <b>60</b> and the volume of the solution that has been connected. Disposable set <b>50</b> using manifold <b>60</b> can operate with up to sixteen, e.g., six liter, bags of solution.

Auto-Connection

0101Referring now to <figref idref="DRAWINGS">FIG. 12</figref>, instrument <b>20</b> in an embodiment includes pinch clamps or pinch valves <b>68</b><i>a </i>to <b>68</b><i>d </i>(referred to collectively herein as valves <b>68</b> or individually as valve <b>68</b>), one valve <b>68</b> for each pigtail <b>46</b><i>a </i>to <b>46</b><i>d </i>of supply bags <b>40</b><i>a </i>to <b>40</b><i>d</i>, respectively (or manifold line <b>64</b> of four-to-one manifold <b>60</b>). Valves <b>68</b><i>a </i>to <b>68</b><i>d </i>are positioned to hold and occlude pigtails <b>46</b><i>a </i>to <b>46</b><i>d</i>, respectively, when (i) connectors <b>56</b> at the end of the pigtails <b>46</b> are attached to a stationary connector holder <b>70</b> and (ii) the tip protectors <b>66</b><i>a </i>protecting each connector <b>56</b> are attached initially to a tip protector removal carriage <b>72</b> of the auto-connection mechanism. Tip protector removal carriage <b>72</b> is also configured to remove spike connector <b>58</b> tip protectors <b>66</b><i>b </i>as shown below. Pinch clamps or valves <b>68</b> are opened, e.g., sequentially, to allow fluid to be withdrawn sequentially from supply bags <b>40</b>. Valves <b>68</b> in an embodiment are closed automatically if there is a need to reload cassette <b>28</b> after supply bags <b>40</b> have been connected. Stationary holder <b>70</b> holds supply bag pigtail connectors <b>56</b> stationary during the auto-connection process.

0102<figref idref="DRAWINGS">FIG. 12</figref> also illustrates a moveable connection carriage <b>74</b>, which holds the organized spike connectors <b>58</b>/tip protectors <b>66</b><i>b </i>at the end of supply lines <b>48</b><i>a </i>connected to cassette <b>28</b>. The individual holders of stationary holder <b>70</b> and moveable carriages <b>72</b> and <b>74</b> are aligned in the Z-direction as shown by the coordinate system in <figref idref="DRAWINGS">FIG. 12</figref>.

0103Moveable carriage <b>72</b> moves in the +X and −X directions to remove tip protectors <b>66</b><i>a </i>from connectors <b>56</b> and tip protectors <b>66</b><i>b </i>from spike connectors <b>58</b>. Moveable carriage <b>72</b> also moves in the +Y and −Y directions to pull the removed tip protectors <b>66</b><i>a </i>and <b>66</b><i>b </i>out of the way for line connection and possibly to reload the tip protectors. Moveable carriage <b>72</b> in an embodiment uses an XY gantry system, which includes a pair of lead screws each driven by a motor, such as a stepper motor. For example, moveable carriage <b>72</b> can be threaded and receive a ball screw supported on two ends by bearings and driven by a stepper motor to move carriage <b>72</b> back and forth in a precise manner in the +X and −X directions. That X-direction assembly can in turn be threaded, e.g., at a bearing support, and receive a ball screw supported on two ends by bearings and driven by a stepper motor to move the X-direction assembly (including carriage <b>72</b>) back and forth in a precise manner in the +Y and −Y directions.

0104Moveable carriage <b>74</b> moves in the +X and −X directions to push spike connectors <b>58</b> of cassette supply lines <b>48</b><i>a </i>into sealed communication with pierceably sealed female connectors <b>56</b> of bag pigtails <b>46</b>. Here, moveable carriage <b>74</b> can be threaded and receive a ball screw supported on two ends by bearings and driven by a stepper motor to move carriage <b>74</b> back and forth in a precise manner in the +X and −X directions.

0105System <b>10</b> is computer controlled and can for example include master processing and memory operating with delegate controllers including delegate processing and memory. Master processor and memory can also operate with a safety controller having safety processing and memory. In one embodiment, master processing and memory operates with a delegate motion controller having processing and memory (e.g., programmable or via an application specific integrated circuit (“ASIC”)), which outputs to the stepper motors and receives inputs, e.g., positional inputs from position sensors.

0106Referring now to <figref idref="DRAWINGS">FIGS. 13A to 13J</figref>, an auto-connection sequence for the sealed mating of connectors <b>56</b> of pigtails <b>46</b> of supply bags <b>40</b> to the spike connectors <b>58</b> of the supply lines of set <b>48</b><i>a </i>(alternatively supply line set <b>48</b><i>b </i>and <b>48</b><i>c </i>as discussed above) of cassette <b>28</b> is illustrated. In <figref idref="DRAWINGS">FIG. 13A</figref>, an organizer holding four spike connectors <b>58</b>/tip protectors <b>66</b><i>b </i>of cassette supply line set <b>48</b><i>a </i>connected to cassette <b>28</b> are loaded into the group holder of moveable carriage <b>74</b>. Alternately, an integrated four-spike bundle with connectors <b>58</b>/tip protectors <b>66</b><i>b </i>is loaded into the group holder of moveable carriage <b>74</b>. In this step, cassette <b>28</b> is also loaded into instrument <b>20</b> (see <figref idref="DRAWINGS">FIGS. 2 and 3</figref>).

0107In <figref idref="DRAWINGS">FIG. 13B</figref>, connectors <b>56</b>/tip protectors <b>66</b><i>a </i>located at the end of four supply bag pigtails <b>46</b> are loaded into individual holders of stationary holder <b>70</b> and moveable carriage <b>72</b>. In particular, connectors <b>56</b> are loaded into individual holders of stationary holder <b>70</b> and tip protectors <b>66</b><i>a </i>are loaded moveable carriage <b>72</b>. Thus in <figref idref="DRAWINGS">FIG. 13B</figref>, tip protectors <b>66</b><i>a </i>and <b>66</b><i>b </i>are set to be removed automatically from connectors <b>56</b>.

0108After spike connectors <b>58</b>/tip protectors <b>66</b><i>b </i>and connectors <b>56</b>/tip protectors <b>66</b><i>a </i>have been loaded into the auto-connection mechanism, a cover or door is closed (not illustrated), isolating holder <b>70</b>, carriages <b>72</b> and <b>74</b>, spike connectors <b>58</b>/tip protectors <b>66</b><i>b </i>and female connectors <b>56</b>/tip protectors <b>66</b><i>a </i>from the environment. System <b>10</b> then injects filtered high-efficiency-particulate-air (“HEPA”) or ultra-low-penetration-air (“ULPA”) into the sealed compartment to reduce the bioburden in the region prior to tip protector removal from connectors <b>56</b> and <b>58</b>. Pneumatic control of HEPA or ULPA air can be located on the motion controller mentioned above or on a separate pneumatic controller operating with the master controller.

0109The imaging system determines which supply bags have been loaded (quantity, size, solution type, expiration date, lot code, etc.) and alerts the user if a problem arises with any of the above identifiers. For example, the solution volume may be insufficient to perform the selected therapy. Alternatively, a connector may be distorted or damaged so that it will not connect properly.

0110In <figref idref="DRAWINGS">FIG. 13C</figref>, moveable carriage <b>72</b> moves in the −X direction (according to coordinate system of <figref idref="DRAWINGS">FIG. 12</figref>) to remove pre-loaded tip protectors <b>66</b><i>a </i>from supply bag connectors <b>56</b>.

0111In <figref idref="DRAWINGS">FIG. 13D</figref>, moveable carriage <b>72</b> moves further in the −X direction (according to coordinate system of <figref idref="DRAWINGS">FIG. 12</figref>) to lock tip protectors <b>66</b><i>b </i>to protecting spike connectors <b>58</b>.

0112In <figref idref="DRAWINGS">FIG. 13E</figref>, moveable carriage <b>72</b> moves in the +X direction (according to coordinate system of <figref idref="DRAWINGS">FIG. 12</figref>) to remove tip protectors <b>66</b><i>b </i>from spike connectors <b>58</b>.

0113In <figref idref="DRAWINGS">FIG. 13F</figref>, moveable carriage <b>72</b> moves in the +Y direction (according to coordinate system of <figref idref="DRAWINGS">FIG. 12</figref>) to move out of the way of supply bag connectors <b>56</b> and spike connectors <b>58</b>.

0114In <figref idref="DRAWINGS">FIG. 13G</figref>, moveable carriage <b>74</b> moves in the +X direction (according to coordinate system of <figref idref="DRAWINGS">FIG. 12</figref>) towards stationary holder <b>70</b> to push spike connectors <b>58</b> into pierceably-sealed supply bag connectors <b>56</b> and to fluidly connect supply bag <b>40</b> to cassette <b>28</b>. After the connections of spike connectors <b>58</b> to supply bag connectors <b>56</b> have been made, an imaging system described below verifies that the connections have been made properly and that no leaks are present.

0115FIG. <b>13</b>H(a) shows one removal embodiment in which a connected supply of set lines <b>48</b><i>a </i>and solution lines or pigtails <b>46</b> and associated empty supply bags <b>40</b> and cassette <b>28</b> are removed from carriage <b>74</b> and holder <b>70</b>, respectively, together. In <figref idref="DRAWINGS">FIG. 13I</figref>, moveable carriage <b>72</b> is then moved in the −Y direction (<figref idref="DRAWINGS">FIG. 12</figref>) to allow the consumed tip protectors <b>66</b><i>a </i>and <b>66</b><i>b </i>to be retrieved.

0116FIG. <b>13</b>H(b) shows another removal embodiment in which moveable carriage <b>74</b> moves in the −X direction to pull connectors <b>56</b> and <b>58</b> apart, after which moveable carriage <b>72</b> moves in the −Y direction (according to coordinate system of <figref idref="DRAWINGS">FIG. 12</figref>) and then back and forth in the + and −X directions to reattach tip protectors <b>66</b><i>a </i>and <b>66</b><i>b </i>to connectors <b>56</b> and <b>58</b>, respectively, allowing supply lines of set <b>48</b><i>a</i>, pigtails <b>46</b> and associated supply bags <b>40</b> and cassette <b>28</b> to be removed from carriages <b>72</b> and <b>74</b> and holder <b>70</b>, respectively. This latter removal method is preferable if it is common that the supply bags will not be completely empty when the bags have to be removed.

Auto-Identification

0117<figref idref="DRAWINGS">FIG. 14</figref> illustrates one embodiment for an auto-identification system. The system includes a color-capture device (“CCD”) camera <b>80</b>, which uses a charge-coupled device image sensor and an integrated circuit containing an array of linked, or coupled, light-sensitive capacitors. Other cameras that create a three-dimensional image of a connection area shown in <figref idref="DRAWINGS">FIG. 14</figref> may be used alternatively. The auto-identification system uses the image from camera <b>80</b> to determine characteristics of solution bags <b>40</b> and to verify that the correct, undamaged connectors <b>56</b> and <b>58</b> are loaded into the mechanism.

0118The auto-identification system accomplishes solution identification via a character recognition routine (located for example on the motion controller or a separate video controller operable with the central processing unit or master controller) that “reads” the codes printed on the pigtail connectors <b>56</b> connected to supply bags <b>40</b>. The “codes” provide (i) solution type, e.g., glucose or bicarbonate concentrate or premixed dialysate, (ii) bag volume, e.g., six liters, and (iii) number of bags per connector <b>56</b>, e.g., single bag or multiple bags via four-to-one manifold <b>60</b>. The image of each connector <b>56</b> is compared against stored images of the range of acceptable geometries for connector <b>56</b>. A deformed connector, or a connector that has been loaded incorrectly, or that does not match therapy prescription will fall outside of a range of acceptable geometries and cause system <b>10</b> to signal an alarm and cause other appropriate action, e.g., closing clamps <b>68</b> or not allowing them to be opened until the alarm is cleared. The imaging system also verifies that the “connected” joints fall within an acceptable range of geometries for a good joint connection. If a joint leaks and droplets form, the imaging system sees the droplets and causes an alarm.

Priming

0119In an embodiment, a dual lumen patient line <b>52</b> (<figref idref="DRAWINGS">FIG. 10</figref>) is used. One lumen is connected to a patient-drain port through a pumping chamber of disposable cassette <b>28</b>. The other lumen is connected to a patient-fill port through a different pumping chamber of the disposable cassette <b>28</b>. During priming of the patient line, the two lumens of the patient line are connected together. Cycler <b>20</b> causes one of the diaphragm pumps of cassette <b>28</b> to pump or push fresh fluid out the patient-fill port on the disposable cassette <b>28</b>, down one lumen of patient line <b>52</b>, until it reaches the end of the patient line. The fresh fluid is then pumped back up the other lumen of patient line <b>52</b>, into cassette <b>28</b> through the patient-drain port and into another diaphragm pump of cassette <b>28</b>, which removes air that the fluid pushes through the patient line <b>52</b>. When fluid fills the second pump chamber, the patient line is fully primed.

Patient Connection/Disconnection

0120Primed dual lumen patient line (with fill lumen <b>52</b><i>a </i>and drain lumen <b>52</b><i>b </i>connected) and transfer set <b>82</b> (with fill line <b>84</b> and drain line <b>86</b> connected) are loaded into a patient line an auto-connection device <b>90</b>, as illustrated in <figref idref="DRAWINGS">FIGS. 15A to 15E</figref>. Device <b>90</b> can be separate from or integrated into instrument <b>20</b>. Instrument <b>20</b> or cart <b>12</b> in an embodiment provides an area and apparatus for storing device <b>90</b>. Device <b>90</b> can be powered or configured for manual or manual/automatic operation. Device <b>90</b> includes a stationary portion <b>92</b> and a portion <b>94</b>, which is rotatable and translatable with respect to stationary portion <b>92</b>.

0121As seen in <figref idref="DRAWINGS">FIG. 15E</figref>, device <b>90</b> includes a cover <b>91</b> and base <b>93</b> which mate (e.g., hingedly or separately) to enclose connectors <b>56</b> (with pierceable membrane) and <b>58</b> (spike) of lumens <b>52</b><i>a </i>and <b>52</b><i>b </i>and lines <b>84</b> and <b>86</b> when loaded into portions <b>92</b> and <b>94</b>. Cover <b>91</b> and base <b>93</b> can be plastic or metal as desired. <figref idref="DRAWINGS">FIG. 15E</figref> also illustrates that device <b>90</b> includes one or more motor <b>95</b> having an output shaft <b>97</b> connected operably to portion <b>94</b> to move (e.g., rotate and/or translate) portion <b>94</b> relative to portion <b>92</b>, which is generally stationary. For example, output shaft <b>97</b> of motor <b>95</b> can drive a ball screw that in turn is connected threadingly to portion <b>94</b>, which enables motor <b>95</b> to translate portion <b>94</b>. In the illustrated embodiment, output shaft <b>97</b> of motor <b>95</b> is coupled to portion <b>94</b> in a manner such that motor <b>95</b> can rotate portion <b>94</b>. A lever <b>99</b> is connected to the subassembly of motor <b>95</b> and moveable portion <b>94</b>, such that the patient or caregiver can translate portion <b>94</b> back and forth with respect to stationary portion <b>92</b> via lever <b>99</b>. Device <b>90</b> is alternatively fully automatic (e.g., AC or battery powered) or fully manual.

0122Device <b>90</b> also includes an apparatus for maintaining an aseptic environment when lumens <b>52</b><i>a </i>and <b>52</b><i>b </i>and lines <b>84</b> and <b>86</b> are pulled apart. For example, device <b>90</b> can employ an ultraviolet (“UV”) light or radiator described in U.S. Pat. Nos. 4,412,834 and 4,503,333, owned by the eventual assignee of the present application, the entire contents of which are incorporated herein by reference. Device <b>90</b> can also introduce HEPA or ULPA filtered air into the volume around the connector prior to connection.

0123Referring additionally to <figref idref="DRAWINGS">FIGS. 15A to 15D</figref>, once the dual lumen patient line <b>52</b> and transfer set <b>82</b> are loaded into device <b>90</b>, the patient line shown here as having fill lumen <b>52</b><i>a </i>(terminating in a female connector <b>56</b> as described above) and drain lumen <b>52</b><i>b </i>(terminating in a spike connector <b>58</b> as described above) are split apart and connected to the patient's transfer set <b>82</b>. Transfer set <b>82</b> includes a fill line <b>84</b> (terminating in a spike connector <b>58</b>) and a drain line <b>86</b> (terminating in a female connector <b>56</b>).

0124In <figref idref="DRAWINGS">FIG. 15A</figref>, fill lumen <b>52</b><i>a </i>is connected via the prime sequence to drain lumen <b>52</b><i>b</i>. Fill line <b>84</b> and drain line <b>86</b> or transfer set <b>82</b> are also connected. Mated connectors <b>56</b> and <b>58</b> of each pair are loaded into device <b>90</b>, such that return lumen <b>52</b><i>b </i>and fill line <b>84</b> (both having spike connectors <b>58</b>) are loaded into stationary portion <b>92</b> of device <b>90</b> and fill lumen <b>52</b><i>a </i>and drain line <b>86</b> (both having female connectors <b>56</b>) are loaded into rotatable portion <b>94</b> of device <b>90</b>. In one embodiment portions <b>92</b> and <b>94</b> are structured such that portion <b>92</b> can only accept spike connectors <b>58</b> and portion <b>94</b> can only accept female connectors <b>56</b>. Cover <b>91</b> of device <b>90</b> is closed and the aseptic apparatus is initiated or energized.

0125In <figref idref="DRAWINGS">FIG. 15B</figref>, portion <b>94</b> via, e.g., electrically actuated stepper motor <b>95</b> coupled to a ball screw (not illustrated), or solenoid (not illustrated), pulls lumens <b>52</b><i>a </i>and <b>52</b><i>b </i>and lines <b>84</b> and <b>86</b> apart, respectively. Portion <b>90</b> includes a carriage holding connectors <b>56</b> of lumen <b>52</b><i>a </i>and line <b>86</b>, which are pulled apart from spike connectors <b>58</b>. Translatable portion <b>94</b> and motor <b>95</b> can be housed completely within device <b>90</b> and sealed from the outside environment.

0126In the illustrated embodiment, the translator is operated manually via lever <b>99</b> that the patient grabs and translates to translate portion <b>94</b> carrying connectors <b>56</b> of lumen <b>52</b><i>a </i>and line <b>86</b> towards/away from spike connectors <b>58</b>. In the illustrated embodiment, a thinner shaft of lever <b>99</b> is sealed to device <b>90</b>, such that the handle portion of lever <b>99</b> remains outside device <b>90</b> and is configured for the patient to grasp and move comfortably. The shaft of lever <b>99</b> is connected to motor <b>95</b>, which in turn is coupled to portion <b>94</b> holding connectors <b>56</b> of lumen <b>52</b><i>a </i>and line <b>86</b>.

0127In <figref idref="DRAWINGS">FIG. 15B</figref>, the aseptic apparatus of device <b>90</b> continues to be energized to prevent the tips of connectors <b>56</b> and <b>58</b> from becoming contaminated.

0128In <figref idref="DRAWINGS">FIG. 15C</figref>, motor <b>95</b> rotates rotatable portion <b>94</b> holding female connectors <b>56</b> one-hundred-eighty degrees relative to stationary portion <b>92</b>, such that return Also in this configuration, fill lumen <b>52</b><i>a </i>of dual lumen patient line <b>52</b> is aligned with fill line <b>84</b> of transfer set <b>82</b>. The aseptic apparatus of device <b>90</b> continues to be energized to prevent the tips of connectors <b>56</b> and <b>58</b> from becoming contaminated.

0129In <figref idref="DRAWINGS">FIG. 15D</figref>, translatable portion <b>94</b> (electric or manual) pushes fill lumen <b>52</b><i>a </i>of dual lumen patient line <b>52</b> towards fill line <b>84</b> of transfer set <b>82</b>, connecting spike connector <b>58</b> to female connector <b>56</b>. Simultaneously, return lumen <b>52</b><i>b </i>of dual lumen patient line <b>52</b> is connected sealingly and operably with drain line <b>86</b> of transfer set <b>82</b>. System <b>10</b> can now perform an initial patient drain to remove the prior procedure's spent last-bag fill and ready the patient for a first fill of the present therapy.

0130It should be appreciated that the sequence of <figref idref="DRAWINGS">FIGS. 15A to 15D</figref> works no matter which side <b>96</b> or <b>98</b> of device <b>90</b> connected lumens <b>52</b><i>a </i>and <b>52</b><i>b </i>and connected lines <b>84</b> and <b>86</b> are loaded in <figref idref="DRAWINGS">FIG. 15A</figref>.

0131In a patient disconnection sequence, connected inflow lines <b>52</b><i>a </i>and <b>84</b> are loaded into one side <b>96</b> or <b>98</b> of device <b>90</b>. Connected outflow lines <b>52</b><i>b </i>and <b>86</b> are loaded into the other side of device <b>90</b>. In a next step, device <b>90</b> (manually or automatically) disconnects cassette inflow line <b>52</b><i>a </i>from transfer set inflow line <b>84</b> and cassette outflow line <b>52</b><i>b </i>from transfer set outflow line <b>86</b>.

0132Next, rotatable portion <b>94</b> holding female connectors <b>56</b> is rotated one-hundred-eighty degrees relative to stationary portion <b>92</b>, such that now return lumen <b>52</b><i>b </i>of dual lumen patient line <b>52</b> is aligned with fill lumen <b>52</b><i>a </i>of dual lumen patient line <b>52</b>, and drain line <b>86</b> of transfer set <b>82</b> is now aligned with fill line <b>84</b> of transfer set <b>82</b>.

0133In a next step, device <b>90</b> (manually or automatically) connects cassette inflow line <b>52</b><i>a </i>to cassette outflow line <b>52</b><i>b </i>and transfer set inflow line <b>84</b> to transfer set outflow line <b>86</b>. Device <b>90</b> provides an aseptic environment for the above four steps. The patient can then remove the connected dual lumen line <b>52</b> and transfer set <b>82</b> from device <b>90</b> and is free from the dialysis instrument.

0134It should be appreciated that device <b>90</b> is not limited to the dual lumen patient line <b>52</b>/transfer set <b>82</b> connection/disconnection application just described or even to APD. For example, a single patient line <b>84</b> having a spike connector <b>58</b> protected by a female cap <b>56</b> could be loaded instead into side <b>98</b> of device <b>90</b>, while a supply bag pigtail <b>46</b> having a female pierceable connector <b>56</b> and a cap is loaded into side <b>96</b> of device <b>90</b>. The female cap <b>56</b> is next removed from male-ended patient line <b>84</b>, while a cap is removed from female-ended supply pigtail <b>46</b> simultaneously from its cap (by pulling rotatable portion <b>94</b> away from portion <b>92</b>). Next, rotatable portion <b>94</b> is rotated with respect to portion <b>92</b>. Afterwards, female portion <b>94</b> is slid towards portion <b>92</b>, mating spike connector <b>58</b> of patient line <b>84</b> with female connector <b>56</b> of supply bag pigtail <b>46</b>, thus connecting a supply bag <b>40</b> to the patient, for example for CAPD. A similar connection could be made connecting the patient to pumping cassette <b>28</b>.

Patient Drain and Fill

0135During patient drain, system <b>10</b> removes effluent from the patient through return lumen <b>52</b><i>b </i>of dual lumen patient line <b>52</b>. When drain is completed and system <b>10</b> advances to a fill cycle, system <b>10</b> delivers fresh fluid to the patient through fill lumen <b>52</b><i>a </i>of dual lumen patient line <b>52</b>. Here, the only effluent that is “recirculated” back to the patient is the small volume of effluent in fill line <b>84</b> of transfer set <b>82</b> and the patient's catheter. Even this volume need not be recirculated to the patient if a dual lumen catheter and transfer set is used. Further, if a dual lumen catheter and dual lumen transfer set is used with system <b>10</b>, system <b>10</b> can perform a multiple pass continuous flow peritoneal dialysis (“CFPD”) therapy. The multiple pass CFPD therapy can employ a single fill, with a long recirculating flow dwell, or the CFPD therapy can be tidal in nature and recirculate flow during at least one of the dwell periods.

Cassette Improvements

0136Referring now to <figref idref="DRAWINGS">FIG. 16</figref>, cassette <b>100</b> illustrates one embodiment of a cassette and method of making same, in which a rigid plastic portion <b>110</b> of the cassette is encapsulated within cassette sheeting <b>102</b>. However, sheeting <b>102</b> is not welded to the sides of the rigid portion <b>110</b>, sheeting <b>102</b> is instead welded to itself. Plastic portion <b>110</b> in one embodiment is rigid and made of acrylonitrile butadiene styrene (“ABS”), acrylic, polyolefin, polycarbonate, polyethylene or polypropylene. Sheeting <b>102</b> in one embodiment is flexible, e.g., for flexing to pump liquid, and opening and closing valve chambers. Sheeting <b>102</b> can be made of polyvinyl chloride (“PVC”), polyethylene, kraton or polyolefin. Also, two or more plies of the different or same materials can be used, wherein the grains of the plies can flow perpendicular to each other to increase strength and minimize the potential for slits, holes and tears. For example, the outside layer opposite the cassette can have good abrasion, puncture and tear resistant properties and a middle layer having good strength properties.

0137Sheeting <b>102</b> is folded to produce a first side <b>104</b><i>a</i>, a second side <b>104</b><i>b</i>, a folded top <b>106</b> and edges <b>108</b><i>a </i>to <b>108</b><i>c </i>as illustrated. Folded sheet <b>102</b> is slid over rigid portion <b>110</b> as shown in <figref idref="DRAWINGS">FIG. 16</figref>. Next, side edges <b>108</b><i>a </i>of sides <b>104</b><i>a </i>and <b>104</b><i>b </i>are welded together and around supply lines <b>48</b>, patient lines <b>52</b> or drain line <b>54</b>. Alternatively, edges <b>108</b><i>a </i>of sides <b>104</b><i>a </i>and <b>104</b><i>b </i>are welded together and around ports extending from rigid portion <b>110</b> (not seen in <figref idref="DRAWINGS">FIG. 16</figref>), to which supply lines <b>48</b>, patient lines <b>52</b> or drain line <b>54</b> are fitted sealingly. Bottom edges <b>108</b><i>b </i>of sides <b>104</b><i>a </i>and <b>104</b><i>b </i>are welded together. Side edges <b>108</b><i>c </i>of sides <b>104</b><i>a </i>and <b>104</b><i>b </i>are welded together. Flexible sheeting <b>102</b> in this manner forms a sealed pouch around rigid portion <b>110</b>. Sides <b>104</b><i>a </i>and <b>104</b><i>b </i>are alternatively separate sheets welded together along four sides.

0138Rigid portion <b>110</b> includes or forms pump chambers <b>112</b>. As described below, an alternative cassette includes three pump chambers. Rigid portion <b>110</b> in the illustrated embodiment also includes a plurality of valve chambers <b>114</b>. Pump chambers <b>112</b> and valve chambers <b>114</b> each include ridges <b>116</b> defining the respective pump or valve chamber, which extend outwardly from a base wall <b>118</b> of rigid portion <b>110</b>. The opposite side of rigid portion includes ridges <b>116</b> extending in the other direction from base wall <b>118</b> and defining flow paths (not seen) that communicate with the pump chambers <b>112</b> and valve chambers <b>114</b>.

0139In operation, side <b>104</b><i>a </i>of sheeting <b>102</b> needs to be sealed to ridges <b>116</b> of the pump and valve chambers for the pneumatic movement and control of fluid. A dialysis instrument operating with pouch cassette <b>100</b>, which has sheeting <b>102</b> sealed to itself around rigid portion <b>110</b> (and to the tubes as discussed above) but not directly to raised ridges <b>116</b>, applies a positive pressure across the surface <b>104</b><i>a </i>relative to rigid portion <b>110</b>. The positive pressure seals surface <b>104</b><i>a </i>to the raised ridges <b>116</b> temporarily during operation so that pumps <b>112</b> and valves <b>114</b> can function properly. Positive pressure is also provided on reverse surface <b>104</b><i>b </i>of sheeting <b>102</b> to compress surface <b>104</b><i>b </i>to raised ridges <b>116</b> of the flow paths (not seen). The positive pressure can be provided pneumatically, e.g., via an inflatable bladder, and/or mechanically, e.g., via spring biasing, solenoid actuation and/or the closing of a door behind which cassette <b>100</b> is loaded.

0140<figref idref="DRAWINGS">FIG. 16</figref> also shows that base wall <b>118</b> can include instrument loading and locating holes <b>120</b>, which enable a locating guide <b>122</b> to be snapped in place after sheeting <b>102</b> has been welded to itself and to tubing <b>48</b>, <b>52</b> and <b>54</b>. In an embodiment, sheeting <b>102</b> is welded via a heat seal process, which uses a die. That same die can also punch aligning holes <b>124</b> through sheeting <b>102</b> to facilitate the installation of the loading/locating guide <b>122</b>.

0141Cassette <b>100</b> includes integrated valve ports <b>114</b>. System <b>10</b> of <figref idref="DRAWINGS">FIGS. 1 to 3</figref> and instrument <b>20</b> of <figref idref="DRAWINGS">FIG. 12</figref> show pinch valves <b>68</b> external to the cassette, which occlude associated tubing. Pinch valves <b>68</b> allow system <b>10</b> to access each of the supply lines independently but also to eliminate the need for the manual clamps that are typically present on cassette supply lines <b>48</b>. Machine <b>20</b>, not the user, occludes supply lines <b>48</b> when it is necessary to do so, for example when bag connections are made and opened to perform the therapy. Supply lines <b>48</b> also need to be occluded after many alarm/failure conditions or if the power fails.

0142The pinch valves <b>68</b> also aid in the drawing of fluid from the solution lines <b>46</b>. For example, the pinch valve <b>68</b> to only the top shelf <b>38</b> can be opened, allowing bag <b>40</b><i>d </i>to drain partially, e.g., more than 50%, before opening valve <b>68</b> to supply bag <b>40</b><i>c </i>on the second-to-top shelf <b>36</b> allowing bag <b>40</b><i>c </i>to drain partially, e.g., more than 50%, before opening valve <b>68</b> to supply bag <b>40</b><i>b </i>on the third-to-top shelf <b>34</b>, allowing bag <b>40</b><i>b </i>to drain partially, e.g., more than 50%, before opening valve <b>68</b> to supply bag <b>40</b><i>a </i>on bottom shelf <b>32</b>. Fluid will flow via gravity into the pumps and air will tend to float to the back of each bag <b>40</b>. Using this sequence, all of supply bags <b>40</b> can be emptied without sucking any air into the solution lines <b>46</b>. If all supply lines <b>48</b> are opened at once, lower bags <b>40</b><i>a </i>and <b>40</b><i>b </i>will become bloated due to the weight of fluid from the upper supply bags <b>40</b><i>c </i>and <b>40</b><i>d. </i>

0143It should be appreciated that flexible pouch cassette <b>100</b> can include valve chambers <b>114</b> or not include valve chambers <b>114</b> if the above described pinch valves <b>68</b> are used instead. Further, it should be appreciated that the apparatuses and methods disclosed in connection with system <b>10</b> and instrument <b>20</b> are not limited to use with pinch valves <b>68</b> and instead can be used with valve chambers <b>114</b> discussed above. Further alternatively, system <b>10</b> can operate with a combination of valve chambers <b>114</b> and pinch valves <b>68</b>, e.g., using cassette-based valve chambers <b>114</b> during treatment and pinch clamps valves <b>68</b> during setup and alarm conditions.

0144Referring now to <figref idref="DRAWINGS">FIGS. 17A</figref>, <b>17</b>B, cassette <b>130</b> illustrates one embodiment of a three pump chamber disposable pumping and valving cassette. <figref idref="DRAWINGS">FIGS. 18A to 18C</figref> illustrate three methods for operating the three pump chambers to achieve desired outputs.

0145Cassette <b>130</b> in the illustrated embodiment includes many of the same structures or types of structures as cassette <b>100</b>, such as rigid portion <b>110</b> having a base wall <b>118</b> with ridges <b>116</b> extending from the base wall <b>118</b> to form pump chambers <b>112</b><i>a </i>to <b>112</b><i>c </i>(referred to herein collectively as chambers <b>112</b> or generally, individually as chamber <b>112</b>). Ridges <b>116</b> also define valve chambers <b>114</b> as described above. Alternatively, cassette <b>130</b> with three valve chambers <b>112</b> operates with pinch valves <b>68</b> and does not use or provide valve chambers <b>114</b>.

0146<figref idref="DRAWINGS">FIG. 17B</figref> illustrates the back side of cassette <b>130</b>. Here, ridges <b>116</b> extending from base wall <b>118</b> define a flow path <b>132</b>. Flow path <b>132</b> includes manifold sections <b>134</b><i>a </i>and <b>134</b><i>b </i>and baffled sections <b>136</b><i>a </i>to <b>136</b><i>f </i>extending between manifold sections <b>134</b><i>a </i>and <b>134</b><i>b</i>. Manifold sections <b>134</b><i>a </i>and <b>134</b><i>b </i>and baffled sections <b>136</b><i>a </i>to <b>136</b><i>f </i>of flow path <b>132</b> enable cross-talk between pump chambers <b>112</b>, so that the flow patterns discussed below in connection with <figref idref="DRAWINGS">FIGS. 18A to 18C</figref> can be achieved as shown in more detail below in connection with <figref idref="DRAWINGS">FIG. 17C</figref>.

0147Cassette <b>130</b> includes flexible sheeting <b>104</b><i>a </i>and <b>104</b><i>b </i>as discussed above. Sheeting <b>104</b><i>a </i>and <b>104</b><i>b </i>can be separate sheets welded or bonded to the sides of rigid portion <b>110</b> and ridges <b>116</b> of pump chambers <b>112</b> and valve chambers <b>114</b>. Alternatively, sheeting <b>104</b><i>a </i>and <b>104</b><i>b </i>is provided via a single sheet <b>102</b> shown above, which includes a folded edge <b>106</b> and welded or bonded edges <b>108</b><i>a </i>to <b>108</b><i>c </i>as shown and described in connection with <figref idref="DRAWINGS">FIG. 16</figref>.

0148<figref idref="DRAWINGS">FIG. 17C</figref> illustrates one possible valve arrangement for the three pump cassette <b>130</b> of <figref idref="DRAWINGS">FIGS. 17A and 17B</figref>. <figref idref="DRAWINGS">FIG. 17C</figref> illustrates the ports extending out the bottom of cassette <b>130</b>, which is one preferable arrangement for air handling because any air in cassette <b>130</b> will tend to rise to the top of the cassette, leaving only fluid to exit the cassette from the bottom. Boxes marked “A” are areas of cassette <b>130</b> that interact with air sensors located within instrument <b>20</b>. Boxes marked “T” are areas of cassette <b>130</b> that interact with temperature sensors located within instrument <b>20</b>. The Box marked “C” is an area of cassette <b>130</b> that interacts with a conductivity sensor located within instrument <b>20</b>.

0149As illustrated, cassette <b>130</b> includes six supply ports, a dedicated to-patient port, a to/from-patient port, a drain port, and an additional port for mixing, further supplying, or sending or receiving fluid from a batch heater. Cassette <b>130</b> includes three pump chambers <b>112</b><i>a </i>to <b>112</b><i>c </i>described above. Valves <b>114</b> in <figref idref="DRAWINGS">FIGS. 17A and 17B</figref> are differentiated via valves V<b>1</b> to V<b>28</b>. The following valve states are merely examples showing different flow regimes achievable via cassette <b>130</b>.

0150Filling the patient with a premixed solution can for example occur by allowing fresh mixed solution into cassette <b>130</b> via valve V<b>16</b>, flowing through the heater via valve V<b>1</b> into pump chamber <b>112</b><i>c</i>. At the same time, pump chamber <b>112</b><i>b </i>pushes the same fluid to patient via open valves V<b>10</b>, V<b>15</b>, V<b>27</b> and the to/from patient port valve. In this regime, to-patient port and valve are not needed. At the same time, pump chamber <b>112</b><i>c </i>can be performing a volume measuring determination as discussed below. In an alternative embodiment, dedicated to-patient port and valve are used as a second outlet to the patient.

0151Draining effluent from the patient can for example occur by allowing effluent into cassette <b>130</b> via to/from patient valve and port, flowing through valves V<b>26</b> and V<b>12</b> into pump chamber <b>112</b><i>a</i>. At the same time, pump chamber <b>112</b><i>b </i>pushes the effluent to drain via open valves V<b>4</b> and the drain valve. In this regime, dedicated to-patient port and valve are not needed. At the same time, pump chamber <b>112</b><i>a </i>can be performing a volume measuring determination as discussed below. In an alternative embodiment, temperature sensor access valve V<b>15</b> can be opened simultaneously to allow temperature of the effluent entering chamber <b>112</b><i>a </i>to be sensed.

0152In a concentrate mixing regime, chamber <b>112</b><i>c </i>can be filling from concentrate supply <b>1</b> through valves V<b>17</b> and V<b>7</b>. Chamber <b>112</b><i>b </i>can be filling from concentrate supply <b>2</b> through valves V<b>20</b> and V<b>9</b>. Chamber <b>112</b><i>a</i>, here acting as an accumulator as described below in <figref idref="DRAWINGS">FIG. 18C</figref>, outputs mixed concentrates via valves V<b>5</b> and V<b>16</b> to a mixer, for example. In an alternative embodiment, a separate mixer is not used, the length of the patient line is sufficient to mix the concentrates, and chamber <b>112</b><i>a </i>outputs alternatively through valves V<b>5</b>, V<b>28</b>, V<b>27</b> and the to/from patient valve collectively to the patient.

0153In a second stroke as described below in <figref idref="DRAWINGS">FIG. 18C</figref>, chambers <b>112</b><i>c </i>and <b>112</b><i>b </i>empty half of their respective concentrates through valves V<b>1</b> and V<b>3</b>, respectively and V<b>5</b> collectively into chamber <b>112</b><i>a</i>. At the same time, chambers <b>112</b><i>c </i>and <b>112</b><i>b </i>empty the other half of their respective concentrates through valves V<b>1</b> and V<b>3</b>, respectively and valve V<b>16</b> collectively to a mixer. In an alternative embodiment, a separate mixer is not used, the length of the patient line is sufficient to mix the concentrates, and chambers <b>112</b><i>c </i>and <b>112</b><i>b </i>empty the other half of their respective concentrates alternatively through valves V<b>1</b> and V<b>3</b>, respectively and valves V<b>28</b>, V<b>27</b> and the to/from patient valve collectively to the patient.

0154In a multi-pass flow regime, chamber <b>112</b><i>c </i>fills with fresh, e.g., premixed, solution from supply <b>1</b> through valves V<b>17</b> and V<b>7</b>. At the same time, chamber <b>112</b><i>b </i>empties fresh solution to the patient via valves V<b>3</b>, V<b>28</b> and the to-patient valve to the patient. At the same time, chamber <b>112</b><i>a </i>fills with effluent from the patient via the to/from patient valve, and valves V<b>26</b> and V<b>12</b>. Here, the fluid can be recirculating because there is no net fluid loss or ultrafiltration (“UF”) taking place.

0155In a UF to drain mode multi-pass flow example, chamber <b>112</b><i>c </i>empties fresh solution to the patient via valves V<b>1</b>, V<b>28</b> and the to-patient valve to the patient. At the same time chamber <b>112</b><i>b </i>fills with effluent from the patient through the to/from patient valve, and valves V<b>26</b> and V<b>10</b>. At the same time, chamber <b>112</b><i>a </i>empties effluent to drain via valve V<b>6</b> and the drain valve. In an alternative UF bag to bag multi-pass mode, chamber <b>112</b><i>a </i>alternatively empties effluent to an empty supply bag, e.g., supply <b>3</b> via valves V<b>11</b>, V<b>24</b> and V<b>25</b>.

0156In a second state of the UF bag to bag multi-pass mode, chamber <b>112</b><i>c </i>fills with fresh, e.g., premixed, solution from supply <b>1</b> through valves V<b>17</b> and V<b>7</b>. At the same time, chamber <b>112</b><i>b </i>empties fresh solution to the patient via valves V<b>3</b>, V<b>28</b> and the to-patient valve to the patient. At the same time, chamber <b>112</b><i>a </i>fills with effluent from the patient via the to/from patient valve, and valves V<b>26</b> and V<b>12</b>.

0157A test can be run to see if a dual or multi-chamber bag has been opened properly. Here one of pump chambers empties fluid to drain, flowing the fluid past conductivity sensor (“C”), which checks to see if the conductivity measured is indicative of a properly mixed solution, in which case therapy can proceed, and an improperly mixed case in which an alarm is generated.

0158<figref idref="DRAWINGS">FIG. 18A</figref> illustrates one pumping sequence for pump chambers <b>112</b> in which a chamber fill stroke (crosshatched segments) is slightly shorter in duration than a chamber empty stroke (diagonal segments), which are separated by relatively short fluid measurement periods (dotted segments). A fluid measurement (amount of fluid pumped) method is discussed in detail below. Also discussed below is a way to eliminate the fluid measurement periods (dotted segments) occurring after the chamber empty strokes (diagonal segments).

0159In one embodiment, a pneumatic actuator applies negative and positive pressure to sheet <b>104</b><i>a </i>to pump fluid into or out of one of pump chambers <b>112</b>. A pump controller, e.g., microprocessor and computer program memory, controls pneumatic actuators to apply positive, negative or no pressure to the appropriate chamber <b>112</b> at the appropriate time. The processor cycles through a program which at any given time tells the processor which state each pump actuator should be in. The processor controls each actuator based upon that cycle.

0160Three pump cassette <b>130</b> provides continuous flow to the patient during fill, while also drawing fluid continuously from the supply bag through an inline heater for example. As seen in <figref idref="DRAWINGS">FIG. 18A</figref>, at any given time at least one pump chamber <b>112</b><i>a </i>to <b>112</b><i>c </i>is delivering fluid to the patient or to an accumulator (one purpose for an accumulator is described below in connection with <figref idref="DRAWINGS">FIG. 18C</figref>). At any given time at least one pump chamber <b>112</b><i>a </i>to <b>112</b><i>c </i>is filling the patient with heated dialysate.

0161As seen in <figref idref="DRAWINGS">FIG. 18A</figref>, at time t<b>1</b>, pump chamber <b>112</b><i>a </i>is at rest for a measurement calculation from a previous emptying stroke, pump chamber <b>112</b><i>b </i>is emptying fluid to the patient, and pump chamber <b>112</b><i>c </i>is filling with fluid. At time t<b>2</b>, pump chamber <b>112</b><i>a </i>is filling with fluid, pump chamber <b>112</b><i>b </i>is still emptying fluid to the patient, and pump chamber <b>112</b><i>c </i>is at rest for a measurement calculation from a previous filling stroke. At time t<b>3</b>, pump chamber <b>112</b><i>a </i>is still filling, pump chamber <b>112</b><i>b </i>is starting a fill stroke, and pump chamber <b>112</b><i>c </i>is emptying. At time t<b>4</b>, pump chamber <b>112</b><i>a </i>is emptying, pump chamber <b>112</b><i>b </i>is filling, and pump chamber <b>112</b><i>c </i>is starting a rest period for measurement calculation. At time t<b>5</b>, pump chamber <b>112</b><i>a </i>is still emptying, pump chamber <b>112</b><i>b </i>is beginning to empty, and pump chamber <b>112</b><i>c </i>is filling. At time t<b>6</b>, pump chamber <b>112</b><i>a </i>is filling, pump chamber <b>112</b><i>b </i>is emptying, and pump chamber <b>112</b><i>c </i>is filling. At time t<b>7</b>, pump chamber <b>112</b><i>a </i>is still filling, pump chamber <b>112</b><i>b </i>is starting a rest period for measurement calculation, and pump chamber <b>112</b><i>c </i>is emptying. At time t<b>8</b>, pump chamber <b>112</b><i>a </i>is starting an emptying stroke, pump chamber <b>112</b><i>b </i>is filling, and pump chamber <b>112</b><i>c </i>is emptying. At time t<b>9</b>, pump chamber <b>112</b><i>a </i>is emptying, pump chamber <b>112</b><i>b </i>is filling, and pump chamber <b>112</b><i>c </i>is starting a fill stroke.

0162While the above sequence is described in connection with fresh fluid either filling the pump chambers <b>112</b><i>a </i>to <b>112</b><i>c </i>or emptying chambers <b>112</b> to the patient, the same sequence can be employed in connection with spent fluid either filling the pump chambers <b>112</b><i>a </i>to <b>112</b><i>c </i>or emptying chambers <b>112</b> to drain. In either case, filling and emptying pump chambers <b>112</b> is continuous when the operation of the three chambers <b>112</b> is superimposed.

0163<figref idref="DRAWINGS">FIG. 18B</figref> shows a similar sequence to that of <figref idref="DRAWINGS">FIG. 18A</figref>. Here, however, the overlap of the filling strokes and emptying strokes is the same. <figref idref="DRAWINGS">FIG. 18B</figref> illustrates that the relative durations of the filling and emptying strokes can be modified to suit a particular pump chamber and actuation configuration. <figref idref="DRAWINGS">FIGS. 18A and 18B</figref> also show that each time an emptying stroke is about to start, another emptying stroke already in progress is going to stay in progress long enough such that the start of the empty stroke can be delayed for a short period of time, e.g., to discharge a small amount of air from the chamber about to start without disrupting the continuity of the fluid emptying. For example, at time T in <figref idref="DRAWINGS">FIG. 18B</figref>, pump chamber <b>112</b><i>a </i>is supposed to start emptying either fresh fluid to the patient or spent fluid to drain. The start of the pump-out stroke could be delayed for a short period of time to discharge air for example, without disrupting the continuous flow because pump chamber <b>112</b><i>c </i>still has some of its emptying stroke remaining.

0164<figref idref="DRAWINGS">FIG. 18C</figref> illustrates a sequence in which fluid is being mixed, e.g., from two sources to make a stable dialysate for the patient. This can be done for either PD or HD, either inline or from bags or containers. Here, pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>are synchronized. Pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>receive fresh fluid that has already been mixed in one embodiment. Alternatively, pump chamber <b>112</b><i>a </i>pumps one fluid, while pump chamber <b>112</b><i>b </i>pumps a second fluid, each to a same line in which the two fluids are mixed properly. Pump chamber <b>112</b><i>c </i>is an accumulator that receives mixed fluid from pump chambers <b>112</b><i>a </i>and <b>112</b><i>b</i>. Pump chamber <b>112</b><i>c </i>outputs to the patient.

0165The system operating the sequence of <figref idref="DRAWINGS">FIG. 18C</figref> is valved or the flow paths of the system are structured such that half of the mixed fluid leaving pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>during the emptying stroke flows to the patient, while the other half flows to fill pump chamber or accumulator <b>112</b><i>c</i>. When pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>are filling, accumulator or pump chamber <b>112</b><i>c </i>sends its mixed fluid volume to the patient. Since all fluid flowing to and from accumulator <b>112</b><i>c </i>has been accounted for in the measurement periods of pump chambers <b>112</b><i>a </i>and <b>112</b><i>b</i>, separate measurement periods for pump accumulator <b>112</b><i>c </i>are not needed. Here, flow to the patient is continuous. Filling from the concentrate sources is intermittent. A similar routine could be used to remove effluent from the patient. Accumulator <b>112</b><i>c </i>is always attempting to fill with effluent from the patient with this routine. When pumps <b>112</b><i>a </i>or <b>112</b><i>b </i>fill, the pumps pull some fluid from accumulator <b>112</b><i>c </i>as well as from the patient. A routine such as one of <figref idref="DRAWINGS">FIG. 18A</figref> or <figref idref="DRAWINGS">FIG. 18B</figref> can also be used instead to pull effluent so that flow from the patient is continuous and smoother.

Cassette Interface Improvements

0166Referring now to <figref idref="DRAWINGS">FIGS. 19 to 22</figref>, pneumatic system <b>150</b> illustrates one embodiment of a disposable cassette pumping interface of the present disclosure. System <b>150</b> includes a disposable cassette <b>140</b>. Disposable cassette <b>140</b> is similar to cassettes <b>100</b> and <b>130</b> described above and includes many of the same components, which are numbered the same. Cassette <b>140</b> includes a rigid housing or portion <b>110</b>. Flexible sheets <b>104</b><i>a </i>and <b>104</b><i>b </i>(not seen in <figref idref="DRAWINGS">FIG. 19</figref>) are welded or bonded to rigid portion <b>110</b>. Alternatively, sheets <b>104</b><i>a </i>and <b>104</b><i>b </i>are formed from the single folded sheet <b>102</b> discussed above in connection with cassette <b>100</b>. Cassette <b>140</b> is shown from the reverse side as that shown in <figref idref="DRAWINGS">FIG. 16</figref> for cassette <b>100</b>. Here, pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>bulge outwardly, showing the reverse side of pump chambers <b>112</b> as shown in <figref idref="DRAWINGS">FIG. 16</figref>. Cassette <b>140</b> can alternatively include the third pump chamber <b>112</b><i>c </i>discussed above in connection with cassette <b>130</b>.

0167Cassette <b>140</b> includes a base wall <b>118</b> as described above. Ridges <b>116</b> extend outwardly from base wall <b>118</b> to form a plurality of flow paths <b>132</b>. The valve chambers <b>114</b> and surfaces of pump chambers <b>112</b> interacting with the cassette sheeting are provided on the opposite side of cassette <b>140</b> than the side that is shown in <figref idref="DRAWINGS">FIG. 19</figref>. Cassette <b>140</b> further includes a plurality of valve ports <b>126</b>, which communicate fluidly with flow paths <b>132</b> and connect sealingly to tubes, such as supply tubes <b>48</b>, patient line <b>52</b> and drain line <b>54</b> shown above for example in connection with <figref idref="DRAWINGS">FIG. 16</figref>.

0168Pneumatic system <b>150</b> includes a membrane gasket <b>145</b>, which is shown in detail in connection with <figref idref="DRAWINGS">FIGS. 20 and 22</figref>. Membrane gasket <b>145</b> press-fits and seals in a plurality of places to a cassette manifold <b>180</b>, which is shown in detail in connection with <figref idref="DRAWINGS">FIGS. 20 and 21</figref>. In particular, cassette manifold <b>180</b> includes a interface plate <b>185</b>, to which membrane gasket <b>145</b> is attached and sealed.

0169Referring now to <figref idref="DRAWINGS">FIGS. 20 and 22</figref>, membrane gasket <b>145</b> is described in detail. Membrane gasket <b>145</b> is made of a suitable compressible and watertight material, such as silicone rubber, ethylene propylene diene monomer (“EPDM”) rubber, viton or other elastomers having a good fatigue life. In one embodiment, membrane gasket <b>145</b> is made of compression molded silicone rubber. Membrane gasket <b>145</b> includes a side <b>146</b>, which interfaces with, and indeed moves with, sheet <b>104</b><i>a </i>of cassette <b>140</b>. Membrane gasket <b>145</b> includes an opposite side <b>154</b>, which interfaces with and seals in various places to interface plate <b>185</b>.

0170Cassette side <b>146</b> of membrane gasket <b>145</b> includes raised pump ridges <b>148</b><i>a </i>and <b>148</b><i>b</i>, which in an embodiment mate with and press seal against raised ridges <b>116</b> shown for example in <figref idref="DRAWINGS">FIGS. 16 and 17A</figref> as forming the shape of pump chambers <b>112</b>. A pneumatic bladder, e.g., contained in the door of instrument <b>20</b>, can be inflated when the door is closed to press a gasketed plate (not shown) against cassette <b>140</b> which, in turn, compresses sheeting <b>104</b><i>a </i>of cassette <b>140</b> against raised ridges <b>148</b><i>a </i>and <b>148</b><i>b</i>, such that ridges <b>148</b><i>a </i>and <b>148</b><i>b </i>form an o-ring-like seal around raised ridges <b>116</b> of pump chambers <b>112</b> of disposable cassette <b>140</b>. This seal is described in U.S. Patent Application No. 2004/019313 A1, entitled, “Systems, Methods and Apparatus for Pumping Cassette Based Therapies”, and U.S. Pat. No. 6,261,065, entitled, “Systems and Methods for Control of Pumps Employing Electrical Field Sensing”, both of which are incorporated herein by reference and are assigned to the eventual assignee of the present disclosure.

0171Cassette facing surface <b>146</b> of membrane gasket <b>145</b> further includes raised ridges <b>152</b> forming an enclosed path which, in the same manner, seals around raised ridges <b>116</b> of valve chambers <b>114</b> of disposable cassette <b>140</b>. <figref idref="DRAWINGS">FIG. 16</figref> shows ten valve chambers <b>114</b>, which are generally aligned with and have the same shape as the ten enclosed ridges <b>152</b> of cassette surface <b>146</b> of membrane gasket <b>145</b>. Again, in an embodiment, enclosed ridges <b>152</b> mate with and press seal against ridges <b>116</b> of valve chambers <b>114</b> of the disposable cassette <b>140</b>.

0172<figref idref="DRAWINGS">FIG. 22</figref> illustrates the opposite surface <b>154</b> of membrane gasket <b>145</b>, which faces and interacts with interface plate <b>185</b> of cassette manifold <b>180</b>. A raised rim <b>156</b> runs along the outside of surface <b>154</b>, so that the gasket holds its shape. An inner plateau <b>158</b> also extends out from surface <b>154</b>. The removal of material between plateau <b>158</b> and raised rim <b>156</b> allows the two structures to move independently when the instrument door is closed and cassette <b>140</b> is pressed between the instrument door and membrane gasket <b>145</b>, which is retained by interface plate <b>185</b>. Raised rim <b>156</b> optionally seals about a raised edge <b>202</b> of interface plate <b>185</b>, helping membrane gasket <b>145</b> to seal to the interface plate and prevent water or particle ingress.

0173Plateau <b>158</b> defines a pair of blind pump wells <b>160</b><i>a </i>and <b>160</b><i>b</i>. Blind pump wells do not extend all of the way through the thickness of membrane gasket <b>145</b>. Instead, pump wells <b>160</b><i>a </i>and <b>160</b><i>b </i>each include sidewalls <b>162</b>, which extend most of the way through the thickness of membrane gasket <b>145</b> but leave a thin blind wall <b>168</b>. As described in detail below, thin walls <b>168</b> move with sheeting <b>104</b> of cassette <b>140</b> residing within pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>of the cassette.

0174In a similar manner, plateau <b>158</b> defines a plurality of blind valve wells <b>164</b>. Blind valve wells <b>164</b> likewise do not extend all of the way through plateau <b>158</b> of membrane gasket <b>145</b>. Instead, blind valve wells include sidewalls <b>166</b> that extend most of the way through plateau <b>158</b> but terminate at blind wall <b>168</b>. Blind wall <b>168</b> of blind valve wells <b>164</b> in turn operate with sheeting cassette <b>104</b><i>a </i>at valve chambers <b>114</b>.

0175Membrane gasket <b>145</b> defines ports or apertures <b>170</b> that extend all of the way through plateau <b>158</b> of membrane gasket <b>145</b>. Accordingly, apertures <b>170</b> are seen on both plateau <b>158</b> of <figref idref="DRAWINGS">FIG. 22</figref> and surface <b>146</b> of <figref idref="DRAWINGS">FIG. 20</figref>. As further seen in <figref idref="DRAWINGS">FIG. 20</figref>, raised pump ridges <b>148</b><i>a </i>and <b>148</b><i>b </i>and raised valve ridges <b>152</b> on surface <b>146</b> of membrane gasket <b>145</b> enclose or encompass pneumatic ports <b>170</b>. As discussed in detail below, pneumatic ports <b>170</b> enable a negative pressure asserted through membrane gasket <b>145</b> to pull blind wall <b>168</b> of blind pump wells <b>160</b><i>a </i>and <b>160</b><i>b </i>and surface <b>168</b> of valve wells <b>164</b> together with sheeting <b>104</b><i>a </i>of cassette <b>140</b>. The configuration makes wall <b>168</b> and sheeting <b>104</b><i>a </i>operate as a single membrane for each of the individual pump chambers <b>112</b> and valve chambers <b>114</b> of the disposable cassette.

0176Membrane gasket <b>145</b> also includes dead spaces <b>172</b> which do not extend all of the way through plateau <b>158</b>. Accordingly, dead spaces <b>172</b> are only seen on the bulk surfaces <b>154</b> of <figref idref="DRAWINGS">FIG. 22</figref>. Dead spaces <b>172</b> remove material from the membrane gasket where it is not needed and, accordingly, enable membrane gasket <b>145</b> to be made more cost effectively.

0177<figref idref="DRAWINGS">FIGS. 20 and 21</figref> illustrate interface plate <b>185</b>. Interface plate <b>185</b> can be made of metal, such as aluminum, or plastic. Various configurations for interface plate <b>185</b> and cassette interface <b>180</b> are discussed below in connection with <figref idref="DRAWINGS">FIGS. 23 to 30</figref>. Interface plate <b>185</b> includes a sidewall <b>186</b>, top wall <b>188</b> and an enclosed edge <b>202</b> extending from top wall <b>188</b>. As discussed above, edge <b>202</b> fits frictionally within rim <b>156</b> of membrane gasket <b>145</b> to help maintain a sealed environment between the two structures.

0178Pump chamber wells <b>190</b><i>a </i>and <b>190</b><i>b </i>are defined in or provided by membrane plate <b>185</b>. Pump wells <b>190</b><i>a </i>and <b>190</b><i>b </i>cooperate with pump chambers <b>112</b><i>a </i>and <b>112</b><i>b </i>respectively of disposable cassette <b>140</b>. In particular, pump wells <b>190</b><i>a </i>and <b>190</b><i>b </i>include pneumatic actuation ports <b>198</b>. When negative air pressure is supplied through ports <b>198</b>, the negative pressure pulls the combination of blind wall <b>168</b> and sheeting <b>104</b><i>a </i>associated with the pump chamber towards the wall of well <b>190</b><i>a </i>or <b>190</b><i>b</i>. This expands the volume between sheet <b>104</b><i>a </i>and pump chamber <b>112</b> of rigid portion <b>110</b> of cassette <b>140</b> causing a negative pressure to be formed within the cassette, which in turn causes a volume of fluid (fresh or spent) to be pulled into the pump chamber <b>112</b>. Likewise, when positive pressure is applied through aperture <b>198</b>, the positive pressure pushes the combination of blind wall <b>168</b> and cassette sheeting <b>104</b><i>a </i>at the pump well <b>190</b>/pump chamber <b>112</b> interface, pushing wall <b>168</b> and sheeting <b>104</b><i>a </i>into or towards pump chamber <b>112</b> of rigid portion <b>110</b>, which in turn dispels or pushes fluid from the respective pump chamber <b>112</b> to the patient or drain.

0179Pump wells <b>190</b><i>a </i>and <b>190</b><i>b </i>each include a wall <b>192</b>. Wall <b>192</b> fits sealingly and snugly within wall <b>162</b> of a respective blind well <b>160</b><i>a </i>or <b>160</b><i>b </i>of membrane gasket <b>145</b>. The sealed interface between walls <b>192</b> of interface plate <b>185</b> and walls <b>162</b> of pump wells <b>160</b><i>a </i>and <b>160</b><i>b </i>further enhances the sealed and separated operation of the various pumps and valves within system <b>150</b>.

0180Interface plate <b>185</b> also includes a plurality of raised valve seats <b>194</b>. In particular, a valve seat <b>194</b> is provided for each blind valve well <b>164</b> of membrane gasket <b>145</b>. Each valve seat <b>194</b> and blind valve well <b>164</b> corresponds to one of the valve chambers <b>114</b> of disposable cassette <b>140</b>. Valve seats <b>194</b> include raised sidewalls <b>196</b> that extend outwardly from top surface <b>188</b> of interface plate <b>185</b>. Valve wells <b>164</b> of membrane gasket <b>145</b> fit snugly around valve seats <b>194</b>, so that walls <b>166</b> of valve walls <b>164</b> seal against walls <b>196</b> of valve seats <b>194</b>.

0181Valve actuation ports <b>198</b> are defined at least substantially at the center of seats <b>194</b>. In an embodiment, the top surfaces of valve seats <b>194</b> slope downwardly towards the actuation ports <b>198</b>. This enables mating blind surface <b>168</b> and cassette sheeting <b>104</b><i>a </i>to be pulled away from valve chambers <b>114</b> of cassette <b>140</b> to open a respective valve to allow fluid to flow therethrough.

0182As seen in <figref idref="DRAWINGS">FIG. 16</figref>, each valve chamber <b>114</b> includes a relatively centrally located protruding volcano-type port. When cassette <b>140</b> is used with system <b>150</b> the volcano ports each become aligned with one of the actuation ports <b>198</b>. When positive pressure is applied through one of the actuation ports <b>198</b>, the positive pressure pushes the cooperating blind wall <b>168</b> and cassette sheeting <b>104</b><i>a </i>at the respective valve seat <b>194</b> and valve chamber <b>114</b> of cassette <b>140</b>, to cover or close the volcano port, closing the respective valve chamber <b>114</b>.

0183As seen best in <figref idref="DRAWINGS">FIG. 21</figref>, interface plate <b>185</b> includes a plurality of gasket seal ports <b>200</b>. A gasket seal port <b>200</b> is provided for each pump well <b>190</b><i>a </i>and <b>190</b><i>b </i>and for each valve seat <b>194</b>. It should be appreciated from viewing <figref idref="DRAWINGS">FIGS. 21</figref> and <b>22</b> that seal ports <b>200</b> mate with apertures <b>170</b> of membrane gasket <b>145</b>. Seal ports <b>200</b> can extend part way or all of the way through apertures <b>170</b>. In an embodiment, apertures <b>170</b> press-fit around ports <b>200</b> to create a sealed fit between ports and the walls defining apertures <b>170</b>.

0184Sealing membrane gasket <b>145</b> on the vertical surfaces <b>196</b> of the protruding valve seats <b>194</b>, walls <b>192</b> of pump wells <b>190</b><i>a </i>and <b>190</b><i>b </i>and vacuum ports <b>200</b> provide multiple seals for the pump areas and valve areas of the cassette interface. That is, besides the membrane gasket side seals, additional compression seals exist between interface plate <b>185</b> and membrane gasket <b>145</b> as well as between gasket <b>145</b> and cassette sheeting <b>104</b><i>a. </i>

0185In one embodiment the face of the membrane gasket <b>145</b> in the thin flexing sections facing the sheeting <b>104</b><i>a </i>above the pump and valve chamber of cassette <b>140</b> is textured. The surface of that same side of membrane gasket <b>145</b> at the thicker sections that compress and seal against the cassette ribs of the pump chambers, valve chambers and flow path separators of cassette <b>140</b> are not textured and have a fine, smooth surface finish for creating a good seal between the cassette sheeting <b>104</b><i>a </i>and the gasket ridges <b>148</b><i>a</i>, <b>148</b><i>b </i>and <b>152</b>.

0186The texturing of the thin sections of membrane gasket <b>145</b> provides flow channels for the air from the vacuum ports to migrate across the face of each of the valve and pump chambers of cassette <b>140</b>. The texturing also tends to prevent membrane gasket <b>145</b> and cassette sheeting <b>104</b><i>a </i>from sticking together when it is time to remove the cassette from the system. It is also contemplated to introduce a small positive pressure through ports <b>200</b> at the end of the therapy to eject the cassette <b>140</b> from the interface plate <b>185</b>. Alternately, positive pressure can be applied through valve actuation ports <b>198</b> (used to close the cassette valve chambers <b>114</b> of cassette <b>140</b> when it is time to remove the cassette. This action bulges membrane gasket <b>145</b> above pump chambers <b>112</b> and valve chambers <b>114</b> and push cassette <b>140</b> away from interface plate <b>185</b>.

0187In operation, negative pressure is applied through ports <b>200</b> and apertures <b>170</b> to pull cassette sheet <b>104</b><i>a </i>tight against blind wall <b>168</b> of membrane gasket <b>156</b> for a given pump chamber or valve chamber. This negative pressure is applied throughout the treatment, regardless of whether a positive pressure or a negative pressure is being applied via the actuation ports <b>198</b> of pump wells <b>190</b><i>a </i>and <b>190</b><i>b </i>and valve seats <b>194</b>.

0188As discussed above, the operation of applying positive and negative pressure to cassette <b>140</b> is computer-controlled. The processor controlling such actuation is also capable of receiving and processing inputs, such as pressure sensor inputs. For example, a pressure sensor can be fitted and applied to sense the pressure within a manifold linking each of valve seal ports <b>200</b>.

0189Using the pressure sensor, the processor in combination with a computer program can perform an integrity test having precision not previously available. Given the above described apparatus, if a hole develops in either membrane gasket <b>145</b> or cassette sheeting <b>104</b><i>a</i>, the vacuum level in the manifold sensed by the sensor begins to degrade. The sensor output to the processor or logic implementor is indicative of the negative pressure degradation. The processor and computer program detect the decreasing signal and output that a leak is present. The output can prompt any of: (i) shutting down therapy, (ii) sounding an alarm, (iii) showing a visual message, and/or (iv) audibly describing that a leak is present to the patient or caregiver.

0190The processor also accepts one or more signal from one or more moisture sensor, such as a conductivity sensor. The one or more sensor is placed in the instrument below cassette <b>140</b>, e.g., in a channeled well beneath cassette <b>140</b>. The output of the conductivity sensor is combined logically with the output of the pressure sensor.

0191The logically combined signals from the pressure and conductivity sensors result in the following diagnostic ability. If a leak is detected, e.g., negative pressure degradation is detected, but no moisture is detected, the leak is logically determined to be from membrane gasket <b>145</b>. That is, cassette <b>140</b> is not leaking fluid into the conductivity sensor. If the leak is detected and fluid is detected, the leak is logically determined to be from cassette <b>140</b>.

0192To the extent that it is feasible to use multiple pressure sensors with individual pump walls <b>190</b><i>a </i>and <b>190</b><i>b </i>and valve seats <b>194</b> or to multiplex one or more pressure sensors, the diagnostic ability of system <b>150</b> can be expended to be able to pinpoint not only which component is leaking, but which area of which component is leaking. For example, the tubing running to ports <b>200</b> could be split between pump tubing and valve tubing. A first pressure sensor could multiplex between the tubing leading to the different pumps to pinpoint a leak in either the first or second pump. The conductivity sensor then tells the system if it is a cassette pump leak or a gasket pump leak. A second pressure sensor could multiplex to look for leaks in the different valves. Valve one to valve five for example might all check-out to be holding pressure, while valve six shows a leak, meaning the portion of the cassette sheeting or gasket in operation with valve six is leaking. The conductivity sensor tells the system if it is the cassette sheeting or the gasket at the valve six position that is experiencing a leak.

0193Another advantage of the cassette interface of the present disclosure is illustrated via <figref idref="DRAWINGS">FIGS. 23</figref>, <b>24</b>, <b>25</b>A and <b>25</b>B, <b>26</b>A and <b>26</b>B. System <b>10</b> in one embodiment uses a Boyle's Law based fluid measurement method taught in U.S. Pat. No. 4,826,482 (“the '482 Patent”), the entire contents of which are hereby incorporated by reference and relied upon. That method operates on the premise that the air being injected into (or evacuated from) pump actuation port <b>198</b> is at the same temperature as the fluid flowing through cassette <b>140</b>, and at the same temperature of the air within reference chambers <b>210</b><i>a </i>and <b>210</b><i>b</i>, which is heated to body temperature or about 37° C. If a temperature difference exists between the dialysate and operating air temperatures, volumetric accuracy is compromised.

0194It is difficult to quickly and accurately measure the temperature of air when the components mounting the temperature sensor are not at the same temperature as the air that is being measured. Also at the present time, a minimum two-hour warm-up time is required before performing a volumetric calibration on the HomeChoice® Pro APD System, which requires that interface plate <b>185</b>, reference chambers <b>210</b><i>a </i>and <b>210</b><i>b</i>, pump chambers <b>112</b> in pumping cassette <b>110</b> and the fluid being pumped all be warmed to about 37° C.

0195<figref idref="DRAWINGS">FIGS. 19 and 20</figref> illustrate that pneumatic solenoid valves <b>203</b> are mounted directly to plate <b>182</b>. <figref idref="DRAWINGS">FIG. 23</figref> illustrates that volumetric reference chambers <b>210</b><i>a </i>and <b>210</b><i>b</i>, which hold a known volume of air, are located on the reverse side <b>204</b> of interface plate <b>185</b> in one embodiment. The purposes and operation of volumetric reference chambers <b>210</b><i>a </i>and <b>210</b><i>b </i>is discussed in the '482 Patent and in detail below in connection with <figref idref="DRAWINGS">FIGS. 27</figref>, <b>28</b>A to <b>28</b>F and <b>29</b>, which disclose an improvement over the '482 Patent method. It is enough now to understand that chambers <b>210</b><i>a </i>and <b>210</b><i>b </i>are used to calculate a volume of fluid pumped through the cassette. The advantage here is that valves <b>203</b> and volumetric reference chambers <b>210</b><i>a </i>and <b>210</b><i>b </i>are placed in close proximity to each other and to the pneumatic pathways to membrane gasket <b>145</b>.

0196For reference, side <b>204</b> of interface plate <b>185</b> in <figref idref="DRAWINGS">FIG. 23</figref> shows actuation ports <b>198</b> and gasket seal ports <b>200</b> as described above in connection with <figref idref="DRAWINGS">FIGS. 20 and 21</figref>. In the illustrated embodiment, reference chambers <b>210</b><i>a </i>and <b>210</b><i>b </i>are blind wells formed in interface plate <b>185</b> with precision to have a fixed and known volume. In an embodiment, a controlled volume (weighed amount) of a highly thermally conductive material such as cooper mesh is placed in volumetric reference chambers <b>210</b><i>a </i>and <b>210</b><i>b</i>, which tends to counter a cooling effect created when high pressure air flows back from the pump chambers into the low pressure reference chambers <b>210</b><i>a </i>and <b>210</b><i>b</i>. Air within pressure reference chamber <b>210</b><i>a </i>and <b>210</b><i>b </i>quickly equilibrates to the temperature of the copper mesh and the walls of the reference chambers.

0197In <figref idref="DRAWINGS">FIG. 23</figref>, interface plate <b>185</b> is formed from a thermally conductive material, such as metal, e.g., aluminum, copper, steel or stainless steel. In the present system, the thermally conductive interface plate <b>185</b> is heated, e.g., by inductively producing a current that flows within interface plate <b>185</b>, causing the plate to heat due to its bulk resistance. Alternatively a resistive heater is conductively coupled to plate <b>185</b>, e.g., via heating strip <b>208</b>.

0198Although not illustrated, a temperature sensing device, such as a thermistor or thermocouple is attached to the manifold, e.g., near reference chambers <b>210</b><i>a </i>and <b>210</b><i>b</i>. The temperature sensor sends a signal back to the processor or logic implementor, which controls a power supply supplying power to the resistive heater or the current providing device, such that the temperature of interface plate <b>185</b> is maintained steady at a desired temperature. In one embodiment, interface plate <b>185</b> is heated to about 36° or 37° C.

0199Referring now to <figref idref="DRAWINGS">FIGS. 24</figref>, <b>25</b>A, <b>25</b>B, <b>26</b>A and <b>26</b>B, system <b>210</b> illustrates an alternative heated cassette interface embodiment that connects to a remotely located valve manifold, such as that used in the HomeChoice® Pro APD System. System <b>210</b> includes alternative interface plate <b>215</b> and a separate heated reference chamber module <b>220</b>. <figref idref="DRAWINGS">FIG. 24</figref> illustrates module <b>220</b> attached to alternative interface plate <b>215</b>. <figref idref="DRAWINGS">FIGS. 25A and 25B</figref> illustrate alternative interface plate <b>215</b> from the front and back, respectively. <figref idref="DRAWINGS">FIGS. 26A and 26B</figref> illustrate the reference chamber module <b>220</b> from the front and back, respectively.

0200Alternative interface plate <b>215</b> in one embodiment is made of plastic, such as injection molded ABS, Dekin®, Noryl®, polycarbonate or any other suitable plastic. A front surface <b>212</b> of plate <b>215</b> provides the cassette interface, which is shaped largely the same as the cassette interface of interface plate <b>185</b>. Interface plate <b>215</b> includes a plurality of valve seats <b>214</b>, each including a raised plateau <b>216</b>. Plateaus <b>216</b> each form a downwardly angled or conical inset <b>218</b>, which defines an actuation port <b>222</b>. In the illustrated embodiment, gasket seal ports <b>200</b> are not illustrated. It should be appreciated however that gasket seal ports <b>200</b> could be added and that the membrane gasket <b>145</b> shown above can be employed with alternative interface plate <b>215</b>.

0201Alternative interface plate <b>215</b> includes alternative pump wells <b>230</b><i>a </i>and <b>230</b><i>b</i>, which each include a plurality of actuation ports <b>232</b> and a conductive metal, e.g., aluminum or cooper, interface <b>234</b>. Interfaces <b>234</b> are shown in the rear view of plate <b>215</b> in <figref idref="DRAWINGS">FIG. 25B</figref> as extending through an aperture <b>236</b> in the back of pump wells <b>230</b><i>a </i>and <b>230</b><i>b</i>. The conductive interfaces <b>234</b> contact the heated reference chambers of heated reference chamber module <b>220</b>, such that heat from the heated reference chambers in turn heats conductive interfaces <b>234</b>. Heated conductive interfaces <b>234</b> in turn heat air present between pump wells <b>230</b><i>a </i>and <b>230</b><i>b </i>and the mated membrane gasket.

0202<figref idref="DRAWINGS">FIGS. 24 and 25B</figref> show pneumatic fittings <b>238</b>, which in one embodiment are connected to a remotely located valve manifold and to the molded plastic interface plate <b>215</b>. Because fittings <b>238</b> direct positive and negative air flowing to the valve seats <b>214</b> (<figref idref="DRAWINGS">FIG. 25A</figref>) or <b>194</b> (<figref idref="DRAWINGS">FIG. 21</figref>) and to the valve wells <b>164</b> of membrane gasket <b>145</b>, the temperature of this air is not relevant to volumetric pumping accuracy. That is, only the air flowing to the pump chambers <b>112</b> of cassette <b>140</b> needs to be heated. Accordingly, module <b>220</b> can be made in a relatively small package, which fits onto interface <b>215</b>.

0203<figref idref="DRAWINGS">FIGS. 26A and 26B</figref> illustrate heated volumetric reference chamber module <b>220</b>. As seen in <figref idref="DRAWINGS">FIG. 26A</figref>, volumetric reference chambers <b>240</b><i>a </i>and <b>240</b><i>b </i>are fitted into a casing <b>242</b> having a sidewall <b>244</b>, a mounting plate <b>246</b> and a cover <b>248</b>. Sidewall <b>244</b>, mounting plate <b>246</b> and cover <b>248</b> can be made of metal or a thermally conductive plastic. Volumetric reference chambers <b>240</b><i>a </i>and <b>240</b><i>b </i>can be formed integrally as part of mounting plate <b>246</b> or be separate items attached to the mounting plate. Heating wires <b>250</b> run to a cartridge style heating element, such as those made by Watlow Electric Manufacturing Company (St. Louis, Mo.), Chromalox Corporation (Pittsburgh, Pa.) or Tempco Electric Heater Corporation (Wood Dale, Ill.) and fit into an, e.g., round, mounting aperture. Heating wires <b>250</b> can also run to resistive heating elements that can for example coil around or otherwise contact volumetric reference chambers <b>240</b><i>a </i>and <b>240</b><i>b </i>so as to heat the volumetric reference chambers conductively, convectively or via radiant energy. Again, a temperature sensor is incorporated into heated module <b>220</b>, so as to provide feedback to a heating controller, which maintains the volumetric reference chambers at a steady and desired temperature, such as 36° or 37° C., or alternatively at an equilibrium or average operating temperature that the corresponding disposable cassette reaches when pumping dialysis fluid.

0204Volumetric reference chambers <b>240</b><i>a </i>and <b>240</b><i>b </i>each include a conductive interface <b>252</b>, which mate with conductive interfaces <b>234</b> of pump wells <b>230</b><i>a </i>and <b>230</b><i>b </i>shown in <figref idref="DRAWINGS">FIGS. 25A and 25B</figref>. Conductive interfaces <b>252</b> are made of a thermally conducting material, such as copper or aluminum. Thus, it should be appreciated that heat from the heating elements is transferred to the reference chambers, which are also conductive aluminum or copper in one embodiment. Heat conducts to conductive interface <b>252</b>, to conductive interfaces <b>234</b> and to the activation air, which is pumped back and forth from reference chambers <b>240</b><i>a </i>and <b>240</b><i>b </i>via valves or fittings <b>254</b>, through actuation ports <b>232</b> of pump wells <b>230</b><i>a </i>and <b>230</b><i>b </i>of interface plate <b>215</b> to the membrane and gasket.

0205Although not shown, a suitable insulating material, can be dispersed around conductive reference chambers <b>240</b><i>a </i>and <b>240</b><i>b </i>and housing <b>242</b> of module <b>220</b>. The insulating material can be insulating wool or fiberglass, for example. The insulative material can also be applied to the tubing running from fittings <b>254</b> to the remotely located valve manifold and back to the pump ports <b>232</b> over the relatively short tubing pathway to further minimize heat loss to the atmosphere. The close proximity of the pneumatic components also lends the configuration to being heated, which enables the components to be kept at a desired, stable temperature. These features reduce temperature related errors in measuring volume of fluid pumped using both the method of the '482 Patent and the improved method discussed below. The remotely located valve manifold can also be heated to further improve volumetric accuracy. The embodiments shown in <figref idref="DRAWINGS">FIGS. 24 to 26</figref> are more complex than the embodiments of <figref idref="DRAWINGS">FIGS. 19 to 23</figref>; however, the latter embodiments move the valves away from the cassette interface and allow the valves to be incased within a sound enclosure.

Real Time Volume Measurement

0206Referring now to <figref idref="DRAWINGS">FIG. 27</figref>, system <b>250</b> illustrates one embodiment for a pneumatic control of dialysis system <b>10</b> described herein. The top of system <b>250</b> represents the components described above in connection with <figref idref="DRAWINGS">FIGS. 19 to 24</figref>, <b>25</b>A, <b>25</b>B, <b>26</b>A and <b>26</b>B. LP, LS, LH, LF, LD, RP, RS, RH, RF, RD represent the valve wells of the membrane gasket and the valve chambers of the disposable cassette. Although ten valves are described here and in <figref idref="DRAWINGS">FIGS. 19 to 24</figref>, <b>25</b>A, <b>25</b>B, <b>26</b>A and <b>26</b>B, more or less valves may be provided based on many factors, such as supply bag capability, whether or not admixing is supported and whether inline or batch heating is used.

0207The valving and pneumatic lines for gasket seal ports <b>200</b> are not shown in <figref idref="DRAWINGS">FIG. 27</figref>. As described above, ports <b>200</b> can be pressurized together such that one or a couple of valves in combination with a manifold running to each of ports <b>200</b> can control all the gasket seal ports <b>200</b>.

0208Left and right pump chambers represent the pump wells of the manifold and pump chambers <b>112</b> of the disposable cassette. VSL and VSR are the volumetric reference chambers discussed above. As illustrated, pressure transducer X-VSL monitors the pressure in reference chamber VSL. Pressure transducer X-VSR monitors the pressure in reference chamber VSR.

0209Valves C<b>0</b> to C<b>4</b> and D<b>1</b> to D<b>5</b> are three way valves <b>238</b> shown in <figref idref="DRAWINGS">FIGS. 24 and 25B</figref>. Valves A<b>0</b> and B<b>4</b> are pump control valves <b>254</b> shown in <figref idref="DRAWINGS">FIG. 26A</figref>. The remainder of valves A, C and D are located elsewhere in instrument <b>20</b>.

0210System <b>250</b> also includes a plurality of positive and negative pressure tanks, NEG T (negative pressure, communicates with chambers VSL and VSR), POS T (positive pressure, communicates with chambers VSL and VSR), NEG P-L (negative pressure, communicates with left pump chamber), NEG P-R (negative pressure, communicates with right pump chamber), POS P-L (positive pressure, communicates with left pump chamber), and POS P-R (positive pressure, communicates with right pump chamber). Separate pressure transducers X-NEG T, X-POS T, X-NEG P-L, X-NEG P-R, X-POS P-L, X-POS P-R monitor the pressure in the respective pressure tanks.

0211The separate pressure and vacuum reservoirs NEG P-L, NEG P-R, POS P-L and POS P-R allow a pressure (vacuum) decay to be measured as fluid is pushed from (pulled into) pumping chambers <b>112</b> as described in detail below.

0212For reference, a piston bellows, which can be located in the door of instrument <b>20</b>, pushes the cassette against the interface plate and an occluder bellows which can unclamp all lines (fail closed) are shown. Both bellows and the occluder are actuated pneumatically in one embodiment.

0213System <b>250</b> also includes a processor or logic implementer operating with computer memory having program code configured to perform the below described real time method. System <b>250</b> can be operated with the heated manifolds discussed above, making the assumption of constant temperature a more correct assumption.

0214Referring now to <figref idref="DRAWINGS">FIGS. 28A to 28F</figref>, an improved method for measuring the volume of fluid pumped via pneumatic actuation is illustrated. <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> illustrate by example how the volume of fluid moved is calculated after its has been moved. Valves shown blackened are closed, while non-shaded valves are open. The actions shown in <figref idref="DRAWINGS">FIGS. 28A and 28B</figref> occur during the relatively short rest measurement periods just prior to a pump-out stroke shown above in connection with <figref idref="DRAWINGS">FIGS. 18A to 18C</figref>. The actions shown in <figref idref="DRAWINGS">FIGS. 28C and 28D</figref> occur during the short rest measurement periods just after the pump-out strokes of <figref idref="DRAWINGS">FIGS. 18A to 18C</figref>.

0215The chamber is full of fluid in <figref idref="DRAWINGS">FIGS. 28A and 28B</figref>. In <figref idref="DRAWINGS">FIG. 28A</figref>, the valve (or valves) between chamber POS T and the pump chamber (e.g., left pump chamber) is (are) open. The valve (or valves) between the pump chamber (e.g., the left pump chamber) and the associated volumetric reference chamber (e.g., VSL) is (are) closed. This allows the pump chamber to become pressurized to the pressure of POS T, e.g., 7 psig. A vent valve (e.g., A<b>1</b> in <figref idref="DRAWINGS">FIG. 27</figref>) is opened such that the pressure in the volumetric reference chamber (e.g., VSL) is zero. Volumetric reference chamber (e.g., VSL) has a known volume of 16.5 milliliters in the illustrated embodiment.

0216In <figref idref="DRAWINGS">FIG. 28B</figref>, the valve states switch such that the valve (or valves) between chamber POS T and the pump chamber (e.g., left pump chamber) is (are) closed. The valve (or valves) between the pump chamber (e.g., the left pump chamber) and the associated volumetric reference chamber (e.g., VSL) is (are) opened. Vent valve (e.g., A<b>1</b>) is closed. This allows the pump chamber to pressurize the volumetric reference chamber (e.g., VSL) to 2.4 psig, causing the pump pressure to drop from 7 psig to 2.4 psig.

0217The processor is configured to calculate the volume of air or gas V_gasbehind the fluid pump chamber when full as follows: <br /><i>V</i>_gas,full=(<i>P</i>_ref,final<i>−P</i>_ref,initial)/(<i>P</i>_{pressl,initial}<i>−P</i>_pressl,final)*<i>V</i>_ref,<br /> wherein

0218P_ref,finalis a final pressure in the volumetric reference chamber (e.g., VSL) after the fluid pump is allowed to pressurize the volumetric reference chamber (e.g., VSL), 2.4 psig in the example;

0219P_ref,initialis the initial pressure in the reference chamber before the fluid pump is allowed to pressurize the volumetric reference chamber (e.g., VSL), zero psig in the example;

0220P_{pump, initial}is an initial pressure in the pressure chamber before the fluid pump is allowed to pressurize the volumetric reference chamber (e.g., VSL), here 7 psig. P_{pressl, final}is a final pressure in the pressure chamber after the medical fluid pump is allowed to pressurize the volumetric reference chamber (e.g., VSL), here 2.4 psig; and

0221V_refis the volume of the reference chamber, here 16.5 milliliters.

0222Thus V_{gas, full}=(2.4−0)/(7−2.4)*16.5 milliliters=8.6 milliliters.

0223Next, the valve chambers <b>114</b> of the disposable cassette are changed such that positive pressure from one of the pump stroke tanks POS P-L and POS P-R (illustrated in <figref idref="DRAWINGS">FIGS. 28E and 28F</figref>) pushes fluid from the pump chamber to the patient or drain. The pump-out stroke is performed in combination with the real time fluid volume measurement shown below in connection with <figref idref="DRAWINGS">FIGS. 28E and 28F</figref>. This is described below with the real time pressure decay method.

0224Next, as shown in <figref idref="DRAWINGS">FIG. 28C</figref> the chamber has already been emptied. The valve (or valves) between chamber X-POS T and the pump chamber (e.g., left pump chamber) is (are) open. The valve (or valves) between chamber X-POS T and the associated volumetric reference chamber (e.g., VSL) is (are) closed. This allows the pump chamber to become pressurized to the pressure of X-POS T, e.g., 7 psig. A vent valve (e.g., A<b>1</b> in <figref idref="DRAWINGS">FIG. 27</figref>) is opened such that the pressure in the volumetric reference chamber (e.g., VSL) is zero. Volumetric reference chamber (e.g., VSL) has the known volume of 16.5 milliliters.

0225In <figref idref="DRAWINGS">FIG. 28D</figref>, the valve states switch such that valve (or valves) between chamber X-POS T and the pump chamber (e.g., left pump chamber) is (are) closed. The valve (or valves) between the pump chamber and the associated volumetric reference chamber (e.g., VSL) is (are) opened. Vent valve (e.g., A<b>1</b>) is closed. This allows the pump chamber to pressurize the volumetric reference chamber (e.g., VSL) to 4.2 psig, causing the pump pressure to drop from 7 psig to 4.2 psig.

0226The processor is configured to perform the same calculation as shown above, this time to calculate the volume of air or gas V_gasbehind the fluid pump chamber when empty: <br /><i>V</i>_gas,empty=(4.2−0)/(7−4.2)*16.5 milliliters=24.75 milliliters.

0227The volume of fluid pumped between the measurement periods of <figref idref="DRAWINGS">FIGS. 28B and 28C</figref> is then: fluid moved V_fluid=empty chamber air volume V_{gas, empty}−full chamber air volume V_{gas, full}which is 24.75 milliliters−8.6 milliliters=16.15 milliliters.

0228Referring now to <figref idref="DRAWINGS">FIGS. 28E and 28F</figref>, the apparatus for performing a real time calculation of fluid pumped is illustrated. Here, pressure decay in the pressure tank driving the pump chamber during the pump-out stroke (POS P-L and POS P-R) is monitored in real time. The processor calculates the volume pumped in real time according to the equation: <br /><i>V</i>_fluid,t=(<i>P</i>_{POS P,initial}<i>/P</i>_{POS P,t}−1)(<i>V</i>_{POS P}<i>+V</i>_gas,full),<br /> wherein

0229P_{POS P, initial}is an initial pressure of the pressure tank POS P-L and POS P-R prior to the pump-out stroke;

0230P_{POS P,t}is a pressure of the second pressure chamber at a time t during the pump-out stroke;

0231V_{POS P}is a known volume of the second pressure chamber; and

0232V_{gas, full}is the calculated volume of gas in the pump chamber when full made above in connection with <figref idref="DRAWINGS">FIGS. 28A and 28B</figref>.

0233The steps of <figref idref="DRAWINGS">FIGS. 28E and 28F</figref> are made between the before and after calculations above, that is, between the steps of <figref idref="DRAWINGS">FIGS. 28B and 28C</figref>. In <figref idref="DRAWINGS">FIG. 28E</figref>, at the beginning of the pump-out stroke, the valve (or valves) between chamber POS T and the pump chamber (e.g., left pump chamber) is (are) closed. The valve (or valves) between chamber POS T and the associated volumetric reference chamber (e.g., VSL) is (are) closed. Vent valve (e.g., A<b>1</b> in <figref idref="DRAWINGS">FIG. 27</figref>) is also closed. The volume of air in the pump chamber V_{gas, full}is known to be 8.6 milliliters as discussed above in connection with <figref idref="DRAWINGS">FIG. 28B</figref>. The volume of fixed volume tank POS P-L or POS P-R is known, e.g., 500 milliliters. The initial pressure P_{POS P, initial}is known, e.g., 1.5 psig.

0234The valve (or valves) between chamber POS P-L or POS P-R is (are) opened beginning the pump-out stroke. At this moment the pressure begins to decay. The processor is configured to sample the pressure readings (P_{POS P,t}) from pressure transducer X-POS P-L or X-POS P-R, for example every twenty milliseconds. The processor also calculates the real time amount of fluid pumped using the above equation and the measurement of P_{POS P,t}. <figref idref="DRAWINGS">FIG. 28F</figref> shows an end of the pump-out stroke and a corresponding end of the pressure decay.

0235<figref idref="DRAWINGS">FIG. 29</figref> shows a chart of what the decay (P_{POS P,t}), and resulting fluid volume (milliliters) calculated according to the above equation, could look like over the pump-out stroke. For ease of illustration, only a few data points are shown. The pressure begins at the time that the pump-out stroke begins. Here, P_{POS P,t}=P_{POS P, initial}, such that the ratio of same is one, causing the first term in the equation and the resulting fluid volume pumped to be zero.

0236At the second pump stroke time in <figref idref="DRAWINGS">FIG. 29</figref>, P_{POS P,t}has dropped to 16.1 psi (absolute), making the first term in the equation above equal to 0.0062, which when multiplied by the combined volume of tank POS P-L or POS P-R (500 milliliters) and the initial volume of air in the pump chamber (8.6 milliliters) yields an absolute volume pumped of (0.0062)*508.6=3.16 milliliters.

0237At the third pump stroke time in <figref idref="DRAWINGS">FIG. 29</figref>, P_{POS P,t}has dropped to 16.00 psia, making the first term in the equation above equal to 0.0125, which when multiplied by the combined volume of tank POS P-L or POS P-R (500 milliliters) and the initial volume of air in the pump chamber (8.6 milliliters) yields an absolute volume pumped of (0.0125)*508.6=6.35 milliliters.

0238At the fourth pump stroke time in <figref idref="DRAWINGS">FIG. 29</figref>, P_{POS P,t}has dropped to 15.90 psia, making the first term in the equation above equal to 0.0189, which when multiplied by the combined volume of tank POS P-L or POS P-R (500 milliliters) and the initial volume of air in the pump chamber (8.6 milliliters) yields an absolute volume pumped of (0.0189)*508.6=9.59 milliliters.

0239At the fifth pump stroke time in <figref idref="DRAWINGS">FIG. 29</figref>, P_{POS P,t}has dropped to 15.80 psia, making the first term in the equation above equal to 0.0253, which when multiplied by the combined volume of tank POS P-L or POS P-R (500 milliliters) and the initial volume of air in the pump chamber (8.6 milliliters) yields an absolute volume pumped of (0.0253)*508.6=12.87 milliliters.

0240At the sixth and final pump stroke time in <figref idref="DRAWINGS">FIG. 29</figref>, which is also illustrated in <figref idref="DRAWINGS">FIG. 28F</figref>, P_{POS P,t}has dropped to 15.70 psia (1.0 psig), making the first term in the equation above equal to 0.0318, which when multiplied by the combined volume of tank POS P-L or POS P-R (500 milliliters) and the initial volume of air in the pump chamber (8.6 milliliters) yields an absolute volume pumped of (0.0318)*508.6=16.19 milliliters.

0241The final absolute fluid volume moved or pumped via the real time algorithm, 16.19 milliliters, is virtually the same as the volume of fluid calculated via the before and after algorithm of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref>, 16.15 milliliters (0.25% difference). The real time method however enables mid-pump stroke volumes to be known. As described above and shown below, there are many uses for the intermediate volumes including but not limited to determining: (i) if a full pump stroke has occurred; (ii) if a line occlusion has occurred; (iii) if a leak has occurred; and (iv) if multiple concentrates have been mixed properly, for example.

0242As discussed above, the real time fluid volume calculation can be used in combination with the before and after fluid volume calculation. It should be appreciated however that the real time fluid volume calculation does not have to be used in combination with the before and after fluid volume calculation. That is, after the determination of V_{gas, full}in <figref idref="DRAWINGS">FIG. 28B</figref>, the system can perform the real time calculation shown in <figref idref="DRAWINGS">FIGS. 28E</figref>, <b>28</b>F and <b>29</b>, without thereafter doing the post stroke reference chamber pressurization and calculation. It is therefore expressly contemplated to not use the post stroke reference chamber pressurization and calculation, which would negate the need for the post stroke fluid measurement periods shown for example in connection with <figref idref="DRAWINGS">FIGS. 18A and 18B</figref> for both fill and empty strokes. The post stroke fluid measurement period can be eliminated for systems that have any number of pump chambers, e.g., one, two or three pump chambers.

0243<figref idref="DRAWINGS">FIGS. 28A to 28F</figref> and <b>29</b> show a pump-out stroke and associated fluid volume measurement. It should be appreciated that the above methodology also applies to a pump-in or fill stroke. Here, the same pump chamber (left or right) and reference chamber (VSL or VSR) are used. The main difference is that negative pressure is used to flex the cassette sheeting, pulling fluid from a supply or a patient into the pump chamber. Thus viewing <figref idref="DRAWINGS">FIG. 27</figref>, negative pressure tank NEG P-L or NEG P-R replaces the positive pressure tanks Pos P-L or Pos P-R in <figref idref="DRAWINGS">FIGS. 28E and 28F</figref>. Negative pressure would be used for example in the fresh fluid and drain fluid filling phases shown below in connection with <figref idref="DRAWINGS">FIGS. 30 and 31</figref> discussed next. The POS T tank remains as shown in <figref idref="DRAWINGS">FIGS. 28E and 28F</figref> as it is used for fluid measurement after the fact (<b>28</b>A through <b>28</b>D) and not in the real time fluid measurement.

0244Referring now to <figref idref="DRAWINGS">FIG. 30</figref>, the real time method above is used in connection with a filling method <b>300</b> for the filling of both pump chambers (left and right) in a dialysis system that employs an inline mixing of dextrose and bicarbonate concentrates to form a biocompatible dialysate for the patient, which is advantageous physiologically for the patient. For ease of illustration, it is assumed that left pump chamber, reference chamber VSL and negative pumping tank NEG P-L control the dextrose pumping. Right pump chamber, reference chamber VSR and negative pumping tank NEG P-R control the bicarbonate pumping. POS T is used for both pump chambers.

0245In step <b>302</b><i>a </i>and <b>302</b><i>b</i>, system <b>250</b> of <figref idref="DRAWINGS">FIG. 27</figref> fills left pump chamber with dextrose and right pump chamber with bicarbonate. Here, it is assumed that the volume of air or gas in the pump chamber prior to the fill has been determined per the method of <figref idref="DRAWINGS">FIGS. 28A and 28B</figref>.

0246In step <b>304</b><i>a </i>and <b>304</b><i>b</i>, the real time calculation of dextrose and bicarbonate using the method described above in connection with <figref idref="DRAWINGS">FIGS. 28A to 28F</figref> is made. One purpose for doing the real time calculation is to determine flowrate. That is, the processor can be further configured to calculate the difference between the instant volume and a previously calculated volume to determine a real time flowrate so long as the time between measurements is known. For example in <figref idref="DRAWINGS">FIG. 29</figref>, the volume deltas are: 3.16 milliliters, 3.19 milliliters, 3.24 milliliters, 3.28 milliliters and 3.32 milliliters. Assuming the time between pressure readings or sample time to be the same between each sample, the above deltas show the flowrate of fluid during the pump out stroke to be gradually increasing (instantaneous rate=volume delta/sample time). This may be normal due to the configuration of the pneumatic pumping system or an anomaly of the particular pump stroke.

0247The real time flowrate information can be used for many purposes. One use is for control of the heater. Copending patent application entitled “Dialysis Fluid Heating Systems”, filed Jul. 5, 2007, patent application Ser. No. 11/773,903, discloses a dialysis fluid heating control algorithm that uses flowrate feedback to control power to the fluid heating element. The flowrate information determined in connection with the real time volume calculations of step <b>304</b><i>a </i>and <b>304</b><i>b </i>is one way to provide the flowrate feedback to the referenced heating control algorithm.

0248In step <b>306</b><i>a </i>and <b>306</b><i>b</i>, the volume measurements of dextrose and bicarbonate using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> is performed. In step <b>308</b><i>a </i>and <b>308</b><i>b</i>, the final real time volume is compared to the final before and after volume. If the difference between the two is outside of a particular amount (e.g., 1 milliliter), method <b>300</b> assumes that air is present in the associated pump chamber. The real time fluid flow measurement is essentially measuring the movement of the pumping chamber sheeting. The after the fact volumetric calculation only equals the real time measurement when no air is present within the pump chamber. If real time and after the fact measurements differ, air can be assumed to be present. If air is present, method <b>300</b> attempts to remove the air, which may require a couple of attempts. Method <b>300</b> tracks the number of attempts via a counter and eventually causes an alarm if air continues to be present.

0249A first step of the air purge subroutine is to determine if a counter is greater than a maximum amount of air removal tries N that method <b>300</b> is willing to make before determining that an alarm should be posted as seen in connection with step <b>310</b><i>a </i>and <b>310</b><i>b</i>. If counter is greater than N (test could alternatively be whether the counter is equal to N), and the allotted number of air removal procedures has been exceeded, method <b>300</b> resets the counter in step <b>312</b><i>a </i>and <b>312</b><i>b</i>, and posts an alarm in step <b>314</b><i>a </i>and <b>314</b><i>b</i>, e.g., an “air in the system alarm”, which can be at least one of an audio alarm, visual alarm, audiovisual alarm, signal sent to a nurse, operator, pager or control center. The user can clear the alarm and resume the therapy. The procedure beginning at step <b>302</b><i>a </i>and <b>302</b><i>b </i>is then repeated. The alarm may or may not reappear.

0250If counter is less than or equal to N (test could alternatively be whether the counter is less than N), and the allotted number of air removal procedures has not been exceeded, method <b>300</b> increases the count by one in step <b>316</b><i>a </i>and <b>316</b><i>b </i>and causes instrument <b>20</b> to perform an “air purge” procedure in step <b>318</b><i>a </i>and <b>318</b><i>b</i>, which can for example involve opening the drain line valve and “burping” the air out of a port of the pump chamber and into the drain line. The procedure beginning at step <b>302</b><i>a </i>and <b>302</b><i>b </i>is then repeated.

0251Returning to the real time volume versus the before and after volume comparison of step <b>308</b><i>a </i>and <b>308</b><i>b</i>, if the difference between the two is inside of a particular range (e.g., 0 to 1 milliliter), method <b>300</b> next determines whether the fill was a complete fill in step <b>320</b><i>a </i>and <b>320</b><i>b</i>. For example, if the volume defined between the cassette pump chambers <b>112</b> and the pump wells of the interface plate when mated is 16.5 milliliters, method <b>300</b> can look to see whether the total volume delivered meets or exceed some amount close to the defined volume, e.g., fifteen milliliters. To perform this step, method <b>300</b> can look to the real time total volume, the before and after volume or both.

0252If not enough fluid has been drawn into the pump chamber, e.g., volume is less than fifteen milliliters and the number of attempts has been exceeded a maximum number of attempts (step <b>322</b><i>a </i>or <b>322</b><i>b</i>), method <b>300</b> checks if a line kink or other fluid flow obstruction is present and attempts to unkink the line or otherwise remove the occlusion. To do so again may take a couple of tries. Method <b>300</b> tracks the number of occlusion removal tries in steps <b>324</b><i>a </i>and <b>324</b><i>b</i>. If no kink or occlusion is present, the fluid source can be determined to be empty.

0253A first step of the occlusion removal subroutine is to increment a count in step <b>324</b><i>a </i>and <b>324</b><i>b</i>. A next step is to determine if the count is greater than a maximum amount of occlusion removal tries N that method <b>300</b> is willing to make before determining that an alarm should be posted. If counter is greater than N (test could alternatively be whether the counter is equal to N), and the allotted number of occlusion removal procedures has been exceeded, method <b>300</b> posts a continuous alarm that the operator needs to correct before therapy can continue.

0254If counter is less than or equal to N (test could alternatively be whether the counter is less than N), and the allotted number of occlusion removal procedures has not been exceeded, method <b>300</b> causes instrument <b>20</b> to perform an “occlusion removal” procedure in step <b>326</b><i>a </i>and <b>326</b><i>b</i>, which can for example involve pushing fluid back to its source or bag in step <b>326</b><i>a </i>and <b>326</b><i>b </i>in an attempt to unkink the line or bag port. A pushback is a push of a pump chamber of fluid back towards the source solution bag that is not allowing the pump chamber to fill with fluid. The pushback will fail if fluid cannot flow back to the source indicating that the source line is kinked or occluded. A real time pressure decay, or lack thereof, can be used to monitor the pushback flow, or lack thereof.

0255If the pushback is not successful as determined in connection with step <b>328</b><i>a </i>and <b>328</b><i>b</i>, system <b>300</b> determines that the source is occluded in step <b>330</b><i>a </i>and <b>330</b><i>b</i>. If the pushback is successful as determined in connection with step <b>328</b><i>a </i>and <b>328</b><i>b</i>, the source is determined to be empty in step <b>332</b><i>a </i>and <b>332</b><i>b</i>. Once an occluded source or empty source is detected, system <b>300</b> can cause an audible or visual alarms to be posted. System <b>300</b> can cause the fill to resume automatically one or two times before posting a non-recoverable alarm that requires user intervention. The counter in step <b>322</b><i>a </i>and <b>322</b><i>b </i>keeps track of the number of times the pushback attempt is made.

0256In step <b>334</b><i>a </i>and <b>334</b><i>b</i>, left and right pump chambers empty their respective concentrates into a line that connects to the patient, which is long enough for the concentrates to mix sufficiently before the dialysate is delivered to the patient. In steps <b>336</b><i>a </i>and <b>336</b><i>b</i>, method <b>300</b> determines using the real time fluid volume method of <figref idref="DRAWINGS">FIGS. 28A to 28F</figref> whether the total dextrose volume delivered has reached the targeted dextrose pump stroke volume delivered and whether the total bicarbonate volume delivered has reached the targeted bicarbonate pump stroke volume delivered, respectively.

0257If the targeted dextrose volume delivered has not been met in step <b>336</b><i>a</i>, fluid delivery continues and method <b>330</b> determines whether the “real time” (dextrose-bicarb) volume difference is greater than ½ milliliters in step <b>338</b><i>a</i>. If not, left pump chamber continues its emptying of dextrose at step <b>334</b><i>a</i>, causing the real time evaluation of step <b>336</b><i>a </i>to be made again. If real time (dextrose-bicarb) volume difference is greater than ½ milliliter in step <b>338</b><i>a</i>, the left patient valve (LP in <figref idref="DRAWINGS">FIG. 27</figref>) is closed momentarily to prevent the left pump chamber from proceeding too far ahead of the right pump stroke volume delivered in step <b>340</b><i>a</i>. Once the volume delivered by the left and right pump chambers is within ½ milliliter, the left pump chamber will resume its emptying of dextrose in step <b>334</b><i>a</i>, causing the real time evaluation of step <b>336</b><i>a </i>to be made again. Delivery of fluid from the left pump will stop when the left pump chamber has emptied, such that the target pump stroke volume has been delivered.

0258If the target bicarbonate volume delivered has not been met in step <b>336</b><i>b</i>, method <b>330</b> determines whether a real time (bicarbonate-dextrose) volume difference is greater than ½ milliliter in step <b>338</b><i>b</i>. If not, right pump chamber continues to empty bicarbonate again in step <b>334</b><i>b</i>, causing the real time evaluation of step <b>336</b><i>b </i>to be made again. If real time (bicarbonate-dextrose) volume difference is greater than ½ milliliter in step <b>338</b><i>b</i>, the right patient valve (RP in <figref idref="DRAWINGS">FIG. 27</figref>) is closed momentarily to prevent the right pump chamber from proceeding too far ahead of the left pump stroke volume in step <b>340</b><i>b</i>. Once the volume delivered by the left and right pump chambers is within ½ milliliter, right pump chamber resumes its emptying of bicarbonate in step <b>334</b><i>b</i>, causing the real time evaluation of step <b>336</b><i>b </i>to be made again. Delivery of fluid from the right pump will stop when the right pump chamber has emptied, such that the target pump stroke volume has been delivered.

0259Once the dextrose and bicarbonate target pump empty volumes are met in steps <b>336</b><i>a </i>and <b>336</b><i>b</i>, respectively, the processor measures the total volumes delivered using the before and after sequence of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> for dextrose and bicarbonate in steps <b>342</b><i>a </i>and <b>342</b><i>b</i>, respectively. In step <b>344</b>, the processor determines whether a cumulative measured dextrose-bicarbonate volume is less than a threshold difference, e.g., one milliliter. The processor also determines whether a cumulative measured bicarbonate-dextrose volume is less than a threshold, e.g., one milliliter. In essence, the processor is determining whether the cumulative delivered volumes of dextrose and bicarbonate are within 1 milliliter.

0260If the cumulative delivered volumes when compared are outside of the threshold range, the processor adjusts the volume for the next pump stroke by calculating a correction factor in step <b>346</b>. For example, if the normal target pump stroke volume is 15 milliliters, the system <b>300</b> will actually deliver a volume of 15 minus the correction factor for the dextrose. If the cumulative dextrose delivered volume exceeds the cumulative delivered bicarbonate volume by 1.2 milliliters, the correction factor is 1.2 milliliters and the next target stroke volume for dextrose is 15−1.2 milliliters=13.8 milliliters.

0261The correction factor is similar when bicarbonate delivered is greater than dextrose delivered by 1 milliliter or more. The correction factor is zero when the cumulative dextrose delivered is less than cumulative bicarbonate delivered.

0262After step <b>346</b>, or if the cumulative pump empty volumes when compared are inside of the threshold range, the processor determines whether the sum of the cumulative dextrose and bicarbonate pump empty volumes is within a range (e.g., one milliliter) of a prescribed or programmed total dextrose and bicarbonate fill volume in step <b>348</b>. If the measured total is within range of the prescribed total, fill phase is complete in step <b>350</b>.

0263If the measured total is outside the range of the prescribed total, the processor determines whether the cumulative measured volume is less than the prescribed pump empty volume by more than the next scheduled set of pump strokes, e.g., 30 milliliters, in step <b>352</b>. If it is, another set of pump strokes is delivered and step <b>352</b> is reached again. Steps <b>354</b> and <b>356</b> calculate the targeted fill volume for the next set of pump strokes. Step <b>356</b> calculates each targeted volume at 15 milliliters less the correction factors calculated in step <b>346</b>. Step <b>354</b> calculates the fill volume to be ½ of the remaining volume (programmed fill—cumulative measured dextrose and bicarbonate). If the remaining volume is 20 milliliters, and the correction factor for dextrose is 1.2 milliliters, the next stroke target volumes for the last set of pump strokes are calculated to be, for example: <br />(20 milliliters+1.2 milliliters)/2−1.2=9.4 milliliters for dextrose<br />(20 milliliters+1.2 milliliters)/2−0=10.6 milliliters for bicarbonate<br /> The target set of pump stroke volumes adds up to 20 milliliters while correcting the cumulative volume of dextrose so that the cumulative dextrose volume equals the cumulative volume of bicarbonate.

0264Referring now to <figref idref="DRAWINGS">FIG. 31</figref>, the real time method above is illustrated in connection with a draining method <b>400</b> for the filling of one of the pump chambers (left or right) with effluent fluid from the patient. For ease of illustration, left pump chamber, reference chamber VSL and negative pumping tank NEG P-L are used in this example. Right pump chamber, reference chamber VSR and negative pumping tank NEG P-R would be performing the same method simultaneously, but asynchronously so that the right pump chamber is filling with effluent when left pump system is emptying and vice versa.

0265Draining method <b>400</b> determines if the drain is flowing properly and if air is present. In step <b>402</b>, left pump chamber is filled with effluent. In step <b>404</b>, the processor determines the real time effluent volume and flow for the fill in the manner described above. In step <b>406</b>, if flowrate is greater than a normal flow minimum rate threshold, e.g., 50 milliliters/minute, method <b>400</b> determines whether the real time volume calculation of effluent fill exceeds a minimum pump stroke volume threshold, e.g., 12 milliliters, in step <b>408</b>. If not, left pump chamber continues to fill with effluent in step <b>402</b>, forming a loop that cycles until the real time volume calculation of effluent fill exceeds the threshold in step <b>408</b>.

0266When the real time volume calculation of effluent fill exceeds the threshold in step <b>408</b>, the measurement of the effluent fill volume using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> is performed in step <b>410</b>. If the real time fluid volume moved is greater than the before and after stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref>, air may have been drawn into the pump chamber when the chamber filled with fluid. The before and after pump stroke method of <b>28</b>A to <b>28</b>D will not be able to distinguish a pump chamber that contains 13 milliliters of fluid and 2 milliliters of air from a pump chamber that contains only 13 milliliters of fluid because the air will compress regardless of which side of the flexible sheeting it resides on, resulting in the same volume calculation. However, the flexible sheeting will move more when it accepts 13 milliliters of fluid and 2 milliliters of air than it would if it had only accepted 13 milliliters. The HomeChoice® System marketed by eventual assignee of the present disclosure attempts to complete the fill of the pump chamber using an alternate source if the pump chamber fill volume is more than 3 milliliters short of the full volume. If the HomeChoice® System cannot fill the pump chamber completely, air is assumed to be present. The contents of the pump chamber are then pumped to drain to eliminate the air. The HomeChoice® System remedy accordingly wastes time and fluid. The pump air detection and discharge regime occurring after step <b>410</b> is discussed below as step <b>438</b> eliminates.

0267Returning to step <b>406</b>, if flowrate calculated via the real time calculation is less than the normal flow minimum rate threshold, e.g., 50 milliliters/minute, method <b>400</b> determines if the real time flowrate is greater than an intermediate or low flowrate threshold, e.g., 30 milliliters/minute, in step <b>412</b>. If the real time flowrate is greater than the intermediate threshold, method <b>400</b> determines if a time T<b>1</b> at which the flowrate is between the intermediate and high-end thresholds (e.g., between 30 and 50 milliliters/minute) is less than a preset time, e.g., 5:00 minutes in step <b>414</b>. If the flowrate has remained between the intermediate and high-end thresholds for longer than the preset time, method <b>400</b> assumes that the patient line may be partially occluded and will attempt to clear the line pushing fresh dialysate toward the patient. If the pushback is unsuccessful an alarm will be posted (step <b>476</b>). If the pushback is successful (determined via the volume using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> in step <b>416</b>) the method either advances to fill (step <b>300</b>) or posts a low drain volume alarm (step <b>482</b>). This routine is discussed in detail below.

0268If the flowrate has remained between the intermediate and high-end thresholds for less than the preset time, method <b>400</b> determines whether the real time volume calculation of effluent fill exceeds a threshold, e.g., 12 milliliters, in step <b>418</b>. If not, timer T<b>1</b> beginning at zero seconds is initiated in step <b>420</b> and left pump chamber continues to fill with effluent in step <b>402</b>, forming a loop that cycles until (i) T<b>1</b> reaches the preset time (e.g., five minutes) in step <b>414</b> or (ii) the real time volume calculation of effluent fill exceeds the threshold (e.g., 12 milliliters) in step <b>418</b>.

0269When the real time volume calculation of effluent fill exceeds the threshold in step <b>418</b>, the measurement of the effluent fill volume using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> is performed in step <b>410</b>. The pump air detection and discharge regime occurring after step <b>410</b> is discussed below at step <b>438</b>.

0270Returning to step <b>412</b>, if flowrate calculated via the real time calculation is less than the intermediate threshold, e.g., 30 milliliters/minute, method <b>400</b> determines if the real time flowrate is greater than a low end no-flow flowrate threshold, e.g., 12 milliliters/minute, in step <b>422</b>. If the real time flowrate is greater than the low end threshold, method <b>400</b> determines if a time T<b>2</b>, at which the flowrate is between the low end and intermediate thresholds (e.g., between 12 and 30 milliliters/minute), is less than a second preset time, e.g., 3:00 minutes in step <b>424</b>. In the illustrated embodiment T<b>2</b> is less than T<b>1</b>, meaning method <b>400</b> does not wait as long at the lower flowrate before running the occlusion routine at step <b>416</b> because an occlusion is more likely at the lower flowrate.

0271If the flowrate has remained between the low end and intermediate thresholds for longer than the second preset time, method <b>400</b> assumes that the patient line may be partially occluded and attempts to clear the line by pushing fresh dialysate towards the patient. If the pushback is unsuccessful an alarm is posted at step <b>476</b>. If the pushback is successful (determined by measuring the pump fill volume using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> in step <b>416</b>), the pump advances to fill (step <b>300</b>) or posts a low drain volume alarm (step <b>482</b>). This routine is discussed in detail below.

0272If the flowrate has remained between the low end and intermediate thresholds for less than the second preset time T<b>2</b>, method <b>400</b> determines whether the real time volume calculation of effluent fill exceeds a threshold, e.g., 12 milliliters, in step <b>426</b>. If not, timer T<b>2</b> beginning at zero seconds is initiated in step <b>428</b> and left pump chamber continues to fill with effluent in step <b>402</b>, forming a loop that cycles until (i) T<b>2</b> reaches the preset time (e.g., three minutes) in step <b>424</b> or (ii) the real time volume calculation of effluent fill exceeds the threshold (e.g., 12 milliliters) in step <b>426</b>.

0273When the real time volume calculation of effluent fill exceeds the threshold in step <b>426</b>, the measurement of the effluent fill volume using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> is performed in step <b>410</b>. The pump air detection and discharge regime occurring after step <b>410</b> is discussed below at step <b>438</b>.

0274Returning to step <b>422</b>, if flowrate calculated via the real time calculation is less than the low end no-flow threshold, e.g., 12 milliliters/minute, method <b>400</b> initiates a third timer T<b>3</b> if the timer has not yet been initiated in step <b>430</b>. If the real time flowrate is less than the low end threshold, method <b>400</b> determines if a time T<b>3</b> at which the flowrate is less than the low end threshold is less than a third preset time, e.g., 1:00 minute in step <b>432</b>. In the illustrated embodiment T<b>3</b> is less than T<b>2</b>, meaning method <b>400</b> does not wait as long at the low end flowrate before running the occlusion routine at step <b>416</b> because an occlusion or an empty patient is more likely at the lower flowrate.

0275If the flowrate has remained under the low end threshold for less than the second preset time T<b>3</b>, method <b>400</b> determines whether the real time volume calculation of effluent fill exceeds a threshold, e.g., 12 milliliters, in step <b>434</b>. If not, and timer T<b>3</b> is not equal to zero seconds, method <b>400</b> causes left pump chamber to reduce suction pressure in step <b>436</b> (e.g., by changing NEG P-L from −1.5 psig to −1.2 psig as indicated in the pneumatic system <b>250</b> of <figref idref="DRAWINGS">FIG. 27</figref>).

0276At step <b>436</b> the patient is likely close to being empty or fully drained. To reduce discomfort in pulling the remaining effluent out of the patient, method <b>400</b> lowers the suction pressure in step <b>436</b>. Left pump chamber continues to fill with effluent in step <b>402</b>, forming a loop that cycles until (i) T<b>3</b> reaches the preset time (e.g., one minute) in step <b>432</b> or (ii) the real time volume calculation of effluent fill exceeds the threshold (e.g., 12 milliliters) in step <b>434</b>.

0277When the real time volume calculation of effluent fill exceeds the threshold in any of steps <b>408</b>, <b>418</b>, <b>426</b> or <b>434</b>, the measurement of the effluent fill volume using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> is performed in step <b>410</b> and a pump air detection check is performed. Here, method <b>400</b> calculates the difference between the real time calculation of effluent removed from the patient via the method of <figref idref="DRAWINGS">FIGS. 28A to 28F</figref> and the volume calculated using the before and after pump stroke method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref>. If the volume difference is less than a threshold difference (e.g., 1 milliliter) in step <b>438</b>, the system assumes that little or no air is present and that normal pumping can continue because any air that may be present will not pass through the pump.

0278If the difference determined in step <b>438</b> is greater than the threshold, method <b>400</b> initiates a fourth timer T<b>4</b> in step <b>440</b> if the timer has not yet been initiated. If the difference has remained out of range for greater than a fourth preset time (e.g., three minutes) as determined in step <b>442</b>, method <b>400</b> posts an air alarm in the system alarm in step <b>444</b>. If (i) the difference has not remained out of range for greater than the fourth preset time as determined in step <b>442</b> or (ii) the difference between the real time and before/after volumes is less than the threshold, method <b>400</b> causes left pump chamber to empty the effluent to drain in step <b>446</b>. However, if T<b>4</b> is greater than three minutes, the system assumes that the pump chamber has been ingesting air from the patient for three minutes and posts an alarm at step <b>444</b>.

0279Step <b>448</b> creates a loop in which left pump chamber continues to empty to drain as long as the drain flow is greater than a threshold value, e.g., 80 milliliters/minute. When drain flow falls below the threshold, method <b>400</b> determines if the real time volume calculation of effluent sent to drain exceeds a threshold volume, e.g., 12 milliliters, in step <b>450</b>. If not, method <b>400</b> determines if drain flow has fallen below a low end threshold, e.g., 12 milliliters/minute, in step <b>452</b>.

0280If drain flow has not fallen below the low end threshold in step <b>452</b>, a longer timer T<b>5</b> is initiated if not initiated already in step <b>454</b>. A loop is created as long as real time volume is less than the threshold, e.g., 12 milliliters, and drain flow remains above the low end threshold, e.g., 12 milliliters/minute and below the upper threshold, e.g., 80 milliliters/minute until timer T<b>5</b> reaches a fifth (longer) preset time (e.g., three minutes) in step <b>456</b>, at which time method <b>400</b> sends an alarm (audio, visual or audiovisual) to check the drain line for an occlusion in step <b>458</b>.

0281If drain flow has fallen below the low end threshold in step <b>452</b>, a shorter timer T<b>6</b> is initiated if not initiated already in step <b>460</b>. Another loop is created as long as real time volume is less than the threshold, e.g., 12 milliliters, and drain flow remains below the low end threshold, e.g., 12 milliliters/minute, until timer T<b>6</b> reaches a sixth (shorter) preset time (e.g., thirty seconds) in step <b>462</b>, at which time method <b>400</b> sends the alarm to check the drain line for an occlusion in step <b>458</b>.

0282When drain flow falls below the threshold in step <b>448</b> and the real time volume calculation of effluent sent to drain exceeds a threshold volume, e.g., 12 milliliters, in step <b>450</b>, method <b>400</b> calculates the total effluent volume sent to drain via the before and after method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> as seen in step <b>464</b>, after which left pump chamber begins another fill of effluent at step <b>402</b>.

0283When any of the timers T<b>1</b>, T<b>2</b> or T<b>3</b> times out in steps <b>414</b>, <b>424</b> or <b>432</b>, respectively, it is possible that the patient line has an occlusion, which could for example be due to fibrin blockage or a partially kinked line. At step <b>416</b>, method <b>400</b> calculates the total effluent pulled from the patient during the current pump stroke using the before and after method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref>. In step <b>466</b>, left pump chamber empties the effluent to drain. In step <b>468</b>, the total effluent volume sent to drain via the before and after method of <figref idref="DRAWINGS">FIGS. 28A to 28D</figref> is calculated, after which left pump chamber pulls a bolus of fresh fluid from a supply bag in step <b>470</b>.

0284Left pump chamber pushes the fresh bolus to the patient via the patient line to verify that fill can be performed and to remove any fibrin blockage or to un-kink the patient line if it is partially occluded due to a kink in step <b>472</b>. If the pushback procedure is not successful, e.g., fluid cannot reach the patient or real time flowrate is below a threshold, as determined in step <b>474</b>, method <b>400</b> in step <b>476</b> posts a patient line occluded alarm via any of the ways discussed above. If the procedure is successful, e.g., fluid reaches the patient and/or real time flowrate is above a threshold, as determined in step <b>474</b>, method <b>400</b> assumes that the patient is empty at step <b>478</b>.

0285After the patient is determined to be empty in step <b>478</b>, a total volume of effluent pulled from the patient is calculated and compared to a minimum drain volume in step <b>480</b>. If total effluent volume is less than a minimum volume, a low drain alarm is posted in step <b>482</b> via any of the techniques described above. If total effluent volume reaches or exceeds the minimum volume, system <b>10</b> employing method <b>400</b> advances to the fill phase <b>300</b> described above in connection with <figref idref="DRAWINGS">FIG. 30</figref>. The minimum volume can be a percentage of the programmed fill volume when draining to empty. When draining to a target volume, for example with a tidal therapy, the minimum volume is the target volume. Method <b>400</b> also monitors the cumulative volume of effluent drained after step <b>410</b>. This cumulative volume is reported as the volume drained when a tidal drain ends while under a normal flow condition. Otherwise, the cumulative drain volume from step <b>480</b> is reported as the volume drained.

Temperature Sensor

0286Referring now to <figref idref="DRAWINGS">FIGS. 32 and 33</figref>, system <b>500</b> illustrates one possible fluid temperature measuring apparatus and method for system <b>10</b>. Temperature measuring system <b>500</b> is advantageous because it is non-invasive. System <b>500</b> measures the temperature of fluid flowing through a portion of disposable set <b>50</b>. For example, system <b>500</b> could measure the temperature of fluid flowing through disposable cassette <b>28</b>, <b>100</b>, <b>130</b>, <b>140</b>, e.g., upstream, downstream or directly at a fluid heating pathway of a cassette used with inline heating. Or, the fluid could be sensed while flowing through one of the fluid lines, such as directly upstream and/or downstream of the fluid heater. Further alternatively, the fluid could be sensed while residing within a bag or container, such as a warmer bag used with batch heating.

0287In the illustrated embodiment, system <b>500</b> includes a housing <b>502</b>, which is part of instrument <b>20</b> of system <b>10</b>. For example, housing <b>502</b> can be integrated into interface plate <b>185</b> described above in connection with <figref idref="DRAWINGS">FIGS. 19 to 21</figref>. When cassette <b>28</b>, <b>100</b>, <b>130</b>, <b>140</b> is loaded into instrument <b>20</b>, a portion of the cassette is pressed against housing <b>502</b>. Housing <b>502</b> can be plastic or metal and should be at least substantially opaque, e.g., to infrared wavelengths. With the cassette <b>28</b>, <b>100</b>, <b>130</b>, <b>140</b> compressed against housing <b>502</b> and the door of instrument or machine <b>20</b> closed on the other side of cassette <b>28</b>, <b>100</b>, <b>130</b>, <b>140</b>, little ambient light reaches the portion of cassette <b>28</b>, <b>100</b>, <b>130</b>, <b>140</b> interfacing with system <b>500</b>.

0288Sheeting <b>102</b> of cassette <b>28</b>, <b>100</b>, <b>130</b>, <b>140</b> includes a portion <b>504</b> transparent, e.g., to infrared wavelengths, and a non-transparent or opaque portion <b>506</b>. Portions <b>504</b> and <b>506</b> are placed adjacent to housing <b>502</b>. Opaque portion <b>506</b> is formed for example via an inking (e.g., ink-jetting), printing or painting (e.g., spray painting) process. Alternatively, opaque portion <b>506</b> is formed via an opaque patch adhered to the disposable item. The size of opaque portion <b>506</b> can range from about ¼ inch by ¼ inch (6.4 mm by 6.4 mm) to about one inch by one inch (2.54 cm by 2.54 cm) or the same size in diameter if circular. Transparent portion <b>504</b> can be the clear sheeting <b>102</b> and can have an infrared target area at least as large as that of opaque portion <b>506</b>. The size of the target area depends upon the infrared sensor selected and the distance that the sensor is mounted away from the target area. For example, a MIKRON M50 infrared sensor suitable for this application has a ½ inch (1.27 mm) target diameter when pressed against the target. The target diameter increases to 1¼ inch (3.18 cm) when the sensor is moved to six inches (15.25 cm) from the target.

0289Temperature measuring system <b>500</b> includes an arm <b>508</b>, which holds a temperature sensor <b>510</b>. Arm <b>508</b> is able to pivot back and forth at a pivot point <b>512</b>, so that temperature sensor <b>510</b> is pointed selectively at either transparent portion <b>504</b> or opaque portion <b>506</b>. Temperature sensor <b>510</b> in one embodiment is an infrared temperature sensor. Suitable infrared temperature sensors <b>510</b> are provided by PerkinElmer (Walthen, Mass.), Dexter Research (Dexter, Mich.), Electro Optical Components (Santa Rosa, Calif.).

0290In the illustrated embodiment, housing <b>502</b> includes electromagnets <b>514</b>. When energized, the electromagnets will push and/or pull on a metal portion of magnetized pivot arm <b>516</b>. Reversing the polarity will cause the polarity orientation to change. Arm <b>508</b> includes a magnetic, e.g., steel, portion <b>516</b>, which is pulled towards one of the electromagnets <b>514</b> when that electromagnet is energized. Electromagnets control the orientation of the infrared temperature sensor so that infrared temperature sensor <b>510</b> can be pointed selectively (i) at opaque portion <b>506</b> to take a first temperature reading, temp_wall, of the sheeting <b>102</b> only as seen in <figref idref="DRAWINGS">FIG. 32</figref> or (ii) at clear portion <b>504</b> to take a second temperature reading, temp_{wall and fluid}, which is a combination (A*temp_wall+B*temp_fluid) of the sheeting <b>102</b> and the fluid within the sheeting <b>102</b> as seen in <figref idref="DRAWINGS">FIG. 33</figref>. A and B are constants dependent upon the film or tube thickness and composition and are determined experimentally.

0291Because temp_wallis measured and known, the fluid temperature temp_fluidcan be calculated using measured temp_walland measured temp_{wall and fluid}according to the equation:

0292<maths id="MATH-US-00001" num="00001"><math overflow="scroll"><mrow><msub><mi>temp</mi><mi>fluid</mi></msub><mo>=</mo><mfrac><mrow><mo>[</mo><mtable><mtr><mtd><mrow><mrow><mi>measured</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><msub><mi>temp</mi><mrow><mi>wall</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mi>and</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><mi>fluid</mi></mrow></msub></mrow><mo>-</mo></mrow></mtd></mtr><mtr><mtd><mrow><mrow><mo>(</mo><mi>A</mi><mo>)</mo></mrow><mo>*</mo><mrow><mo>(</mo><mrow><mi>measured</mi><mo>⁢</mo><mstyle><mspace width="0.8em" height="0.8ex" /></mstyle><mo>⁢</mo><msub><mi>temp</mi><mi>wall</mi></msub></mrow><mo>)</mo></mrow></mrow></mtd></mtr></mtable><mo>]</mo></mrow><mi>B</mi></mfrac></mrow></math></maths><img file="US7909795B2_D0001.tif" />

0293A processor and memory on a temperature controller or at a central processing unit store constants A and B and perform the above calculation. Temperature sensing system <b>500</b> should provide near real time, non-invasive monitoring of the fluid temperature.

0294Sensor <b>510</b> is flipped back and forth and the different temperature measurements are taken for example, every second. Alternatively, two independent infrared temperature sensors are used, one for infrared energy transmissive portion <b>504</b> and the other for infrared energy non-transmissive portion <b>506</b>. Further, alternatively, a dual or quadruple infrared sensor package is used, such as a Perkinselmer® TPS 2534 dual element thermopile or TPS-4339 Quad Element thermopile. The quad element system provides redundant temperature measurement. Multiple sensors remove calibration complexity.

0295A motor or solenoid could be used instead of electromagnets. Further alternatively, arm <b>508</b> could be pushed by a spring to one pivot position and pneumatically retracted to the second pivot position.

0296Referring now to <figref idref="DRAWINGS">FIG. 34</figref>, data illustrating the accuracy of fluid sensing system <b>500</b> is shown. System <b>500</b> in <figref idref="DRAWINGS">FIG. 34</figref> appears to provide temperature readings non-invasively that approach the accuracy and response time of an invasive temperature sensor. The correlation between the readings from a resistance temperature detector (“RTD”) sensor immersed in the fluid to the calculated readings from infrared sensing system <b>500</b> is good especially considering that the fluid temperature rose from just over 20° C. to over 50° C. during a ten minute time span in which the temperature readings were taken. In the example, constant A was set to 0.877985 and constant B was set to 0.109635. The curve fit line was found to be T_CALC=1.047*T_RTD−0.0303.

Multi-Chamber Bag Open Sensor

0297Referring now to <figref idref="DRAWINGS">FIGS. 35 and 36</figref>, inductive sensing system <b>530</b> illustrates one embodiment for detecting: (i) whether a single chamber supply bag <b>40</b> (referring generally to supply bags <b>40</b><i>a </i>to <b>40</b><i>d </i>discussed above) or a multi-chamber supply bag <b>540</b> is residing on a particular one of shelves <b>32</b>, <b>34</b>, <b>36</b> and <b>38</b>; and (ii) if the supply bag is a multi-chamber supply bag <b>540</b>, whether an associated frangible seal <b>542</b> has been broken allowing two or more concentrates <b>544</b><i>a </i>and <b>544</b><i>b </i>from separate chambers <b>546</b><i>a </i>and <b>546</b><i>b</i>, respectively, to mix.

0298Multi-chamber supply bag inductive sensing system <b>530</b> measures current, which for a fully opened container is indicative of either electrical conductivity or electrical impedance. The measured current indicates whether frangible seal <b>542</b> between chambers <b>546</b><i>a </i>and <b>546</b><i>b </i>of multi-chamber bag <b>540</b> has been broken so that previously separated solutions can mix prior to delivery to a patient.

0299The different concentrates <b>544</b><i>a </i>and <b>544</b><i>b </i>within separate chambers <b>546</b><i>a </i>and <b>546</b><i>b </i>of multi-chamber bag <b>540</b> have different concentrations of ions. The different ionic nature of different concentrates <b>544</b><i>a </i>and <b>544</b><i>b </i>provides an opportunity to correlate a measured current in a mixed solution to a conductivity or impedance of the solution. System <b>530</b> can thereby compare the determined conductivity or impedance with an expected conductivity or impedance to confirm whether the concentrates have been mixed properly. System <b>530</b> is non-invasive, which is advantageous when dealing with sterile medical fluids, such as dialysis fluids. It should be appreciated that system <b>530</b> can also operate with non-sterile or non-injectable fluids.

0300System <b>530</b> includes a first coil <b>532</b> and a second coil <b>534</b>, which are located in different positions within the limits of the tray or shelf (e.g., one of shelves <b>32</b> to <b>38</b>) onto which multi-chamber bag or container <b>540</b> is placed for treatment. For example, coils <b>532</b> and <b>534</b> are installed on top of or underneath the tray or shelf (e.g., one of shelves <b>32</b> to <b>38</b>) or are laminated within the tray or shelf. If installed on top of the tray, coils <b>532</b> and <b>534</b> can be covered with a protective coating or layer. Coils <b>532</b> and <b>534</b> can for example be formed from single stranded wire or multi-stranded wire, such as litzwire. In the illustrated embodiment, coils <b>532</b> and <b>534</b> are pancake or flat coils.

0301One of coils <b>532</b> and <b>534</b> performs a transmitter function while the other of the coils performs a receiver function. The coils can be dedicated to one of the functions, e.g., coil <b>532</b> transmits and coil <b>534</b> receives as shown in <figref idref="DRAWINGS">FIGS. 36 and 37</figref>. Alternatively, coils <b>532</b> and <b>534</b> alternate between the transmitter and receiver functions.

0302A signal (voltage or current) generator <b>536</b> excites transmitter coil <b>532</b> with a signal that varies with time, such as sine wave, square wave, sawtooth wave or other time variable wave. Generator <b>536</b> can be for example (i) a logic level oscillator, (ii) a combination of oscillator and filter or (iii) a waveform generator circuit. One suitable voltage range includes four to twenty volts. Transmitter coil <b>532</b> induces small currents in the dialysate, while receiver coil <b>534</b> senses those currents. The intensity of the currents that receiver coil <b>534</b> senses depends on the type of solution and the degree of electrical coupling between bags and coils <b>532</b> and <b>534</b>. For example, if the shape of the supply bag or container is such that its footprint does not project on top of a receiver coil, the receiver coil will not sense any current. If the shape of the supply bag or container is such that its footprint does not project on top of a transmitter coil, the transmitter coil will induce no current or relatively little current into the solution.

0303<figref idref="DRAWINGS">FIG. 35</figref> shows that unopened seal <b>542</b> causes container <b>540</b> to couple less effectively with the flat areas of chambers <b>546</b><i>a </i>and <b>546</b><i>b </i>that lie flat on the tray or shelf. Accordingly, a sensor or measuring device <b>538</b> will measure less current from receiver coil <b>534</b>. This level of current in <figref idref="DRAWINGS">FIG. 35</figref> is shown to reside in a “not mixed” range. Current measuring device <b>538</b> in one embodiment is a multimeter or an ammeter.

0304<figref idref="DRAWINGS">FIG. 36</figref> shows that opened seal <b>542</b> couples equally effectively with the flat areas of chambers <b>546</b><i>a </i>and <b>546</b><i>b</i>, since the entire bag or container now lies flat on the tray or shelf. Accordingly, sensor or measuring device <b>538</b> measures more current from receiver coil <b>534</b>. This level of current in <figref idref="DRAWINGS">FIG. 36</figref> is shown to reside in a “mixed” range.

0305<figref idref="DRAWINGS">FIGS. 37A to 37D</figref> illustrate an inductive system <b>560</b> that can determine whether bag <b>540</b> is positioned and oriented correctly on tray or shelf <b>32</b>, <b>34</b>, <b>36</b> or <b>38</b>. Bag <b>540</b> shown from the top in <figref idref="DRAWINGS">FIGS. 37A to 37D</figref> shows frangible seal <b>542</b> separating chambers <b>546</b><i>a </i>and <b>546</b><i>b</i>. System <b>560</b> includes four coils <b>532</b><i>a</i>, <b>532</b><i>b</i>, <b>534</b><i>a </i>and <b>534</b><i>b</i>. Each coil can be used for either transmission or reception. The arrows represent some of the possible couplings between the coils.

0306<figref idref="DRAWINGS">FIG. 37A</figref> illustrates a proper loading of bag <b>540</b>, in which a port or pigtail <b>548</b> of bag <b>540</b> is aligned with and rests in aperture <b>35</b> of tray or shelf <b>32</b>, <b>34</b>, <b>36</b> or <b>38</b>. Here, seal <b>542</b> separates coils <b>532</b><i>a </i>and <b>532</b><i>b </i>from coils <b>534</b><i>a </i>and <b>534</b><i>b</i>, respectively. Seal <b>542</b> does not separate coil <b>532</b><i>a </i>from coil <b>534</b><i>a </i>or coil <b>534</b><i>a </i>from coil <b>534</b><i>b</i>. The proper loading position or orientation of <figref idref="DRAWINGS">FIG. 37A</figref> therefore results in a signature inductive coupling pattern of (i) coil <b>532</b><i>a </i>to coil <b>532</b><i>b</i>—high coupling, (ii) coil <b>534</b><i>a </i>to coil <b>534</b><i>b</i>—high coupling, (iii) coil <b>532</b><i>a </i>to coil <b>534</b><i>a</i>—low coupling, and (iv) coil <b>532</b><i>b </i>to coil <b>534</b><i>b</i>—low coupling.

0307The improperly loaded bag <b>540</b> of <figref idref="DRAWINGS">FIG. 37B</figref> on the other hand results in a different inductive coupling pattern of (i) high coupling, (ii) high coupling, (iii) high coupling, and (iv) high coupling because all four coupling coils are located on one side of frangible seal <b>542</b>. The improperly loaded bag <b>540</b> of <figref idref="DRAWINGS">FIG. 37C</figref> results in still a different inductive coupling pattern of (i) low coupling, (ii) low coupling, (iii) high coupling, and (iv) high coupling due the position of seal <b>542</b> relative to the coils illustrated in <figref idref="DRAWINGS">FIG. 37C</figref>. The improperly loaded bag <b>540</b> of <figref idref="DRAWINGS">FIG. 37D</figref> results in the same inductive coupling pattern of <figref idref="DRAWINGS">FIG. 37C</figref>, namely, (i) low coupling, (ii) low coupling, (iii) high coupling, and (iv) high coupling due the position of seal <b>542</b> relative to the coils illustrated in <figref idref="DRAWINGS">FIG. 37D</figref>.

0308A system controller takes the four measurements before seal <b>542</b> is broken and categorizes the coupling signature into either a bag properly loaded state or an improperly loaded state. The electronics of system <b>10</b> in one embodiment include a multiplexer that sequences through each of transmitter/receiver pairs (i) to (iv) upon receiving a signal from a load cell detecting that a bag has been loaded or upon receiving an input from the user that a bag or bags have been loaded. A single signal source <b>536</b> can be multiplexed to a desired coil functioning as the transmitter for the particular pair being sensed, e.g., coil <b>532</b><i>a </i>for pair (i), coil <b>534</b><i>a </i>for pair (ii), coil <b>532</b><i>a </i>for pair (iii), and coil <b>534</b><i>a </i>for pair (iv) shown above. The multiplexer also sequences through a plurality of electrical switch states to electrically connect the appropriate coils of each pair (i) to (iv) to source <b>536</b> and sensor <b>538</b> at the appropriate time.

0309It is also possible, after determining that bag <b>540</b> has been loaded properly, that the controller can verify from the inductive coupling signature that the composition of concentrate solutions <b>544</b><i>a </i>and <b>544</b><i>b </i>in compartments <b>546</b><i>a </i>and <b>546</b><i>b </i>is correct according to an expected conductivity for each solution. Tested pairs (iii) and (iv) for the correct bag position of <figref idref="DRAWINGS">FIG. 37A</figref> reveal the conductivity for concentrates <b>544</b><i>a </i>and <b>544</b><i>b </i>of compartments <b>546</b><i>a </i>and <b>546</b><i>b</i>, respectively. If a conductivity is out of an expected range an error can be generated. The controller can also verify the integrity of seal <b>542</b>. Before allowing treatment to begin, system <b>560</b> also verifies that seal <b>542</b> has been opened allowing concentrates <b>544</b><i>a </i>and <b>544</b><i>b </i>to mix. Once the solution is mixed, the conductivity of the mixed dialysate can also be checked.

0310Correct bag positioning is useful for systems that use gravity for any of the treatment operations. Verification of each of the individual solutions allows determining if concentrations are adequate for the intended treatment. Verification of the integrity of the seal allows instrument <b>12</b> to ascertain that the solutions have not been mixed before treatment has begun. Premature mixture of the solutions considerably shortens the shelf life of the product. Such measurement ensures that no degradation of the solution has occurred.

0311The above-mentioned controller can operate directly or indirectly with a central processing unit, which in turn operates with a video controller and graphical user interface (“GUI”). If all of the above checks are verified, system <b>10</b> causes GUI to display a “bag loading ok” or similar message and allows therapy to continue. If one of the bags <b>540</b> is loaded incorrectly, system <b>10</b> causes GUI to display a “check bag loading” or similar message and perhaps even identifies the bag, e.g., “check loading of second bag from top”. If the bags <b>540</b> are loaded correctly but system <b>560</b> detects an abnormal conductivity, system <b>10</b> causes GUI to display a “check solution of bags loaded” or similar message and perhaps even identifies the bag, e.g., “check solution in second bag from top”. If bag loading and concentration are verified but the user tries to begin therapy without opening one or all of bags <b>54</b>, system <b>10</b> causes the GUI to display a “open bag seal prior to treatment” or similar message and perhaps even identifies the bag, e.g., “open seal of top bag prior to treatment”.

0312<figref idref="DRAWINGS">FIGS. 4 to 9</figref> illustrate a bag management system <b>30</b>, which holds multiple supply bags at an angle for fluid flow and air handling purposes. It should be appreciated that inductive sensing systems <b>530</b> and <b>560</b> can operate at the bag angle of system <b>30</b>, alternatively with bags <b>540</b> loaded at least substantially horizontally or further alternatively with bags <b>540</b> loaded at least substantially vertically. In slanted system <b>30</b>, the coils can be laminated to an upper or lower surface of each tray or be embedded in the tray. With a vertical manager, the coils can be connected to one or more vertical bar that runs vertically up one of the bags and presses respective coils against each bag. Signals to the coils are supplied through vertical support bars. The bag management systems can supply additional information such as weight information via a load cell.

0313It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.